Sealing device and sealing structure

ABSTRACT

The sealing device includes: an outer peripheral ring  2000  that is in contact with a side wall surface of an annular groove  4100  at a low pressure side (L), and slides with respect to an inner peripheral surface of a shaft hole in a housing  5000  through which a shaft  4000  is inserted. An inner peripheral ring  3000  made of a rubber-like elastic body that is in contact with an inner peripheral surface of the outer peripheral ring  2000  and a groove bottom surface of the annular groove  4100 , respectively. The outer peripheral ring  2000  is formed on its outer peripheral surface with a concave portion  2220  which extends from an end of a high pressure side (H) to a position which does not arrive at an end of a low pressure side, so as to introduce fluid thereinto from the high pressure side.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/JP2013/056653, filed Mar. 11, 2013, which claims priority to:Japanese Patent Application No. 2012-054614, filed Mar. 12, 2012;Japanese Patent Application No. 2012-057617, filed Mar. 14, 2012;Japanese Patent Application No. 2012-084544, filed Apr. 3, 2012;Japanese Patent Application No. 2012-125009, filed May 31, 2012;Japanese Patent Application No. 2012-130693, filed Jun. 8, 2012;Japanese Patent Application No. 2012-149282, filed Jul. 3, 2012;Japanese Patent Application No. 2012-175150, filed Aug. 7, 2012;Japanese Patent Application No. 2012-175151, filed Aug. 7, 2012;Japanese Patent Application No. 2012-177232, filed Aug. 9, 2012;Japanese Patent Application No. 2012-201402, filed Sep. 13, 2012;Japanese Patent Application No. 2012-201403, filed Sep. 13, 2012;Japanese Patent Application No. 2012-202870, filed Sep. 14, 2012;Japanese Patent Application No. 2012-225731, filed Oct. 11, 2012;Japanese Patent Application No. 2012-256323, filed Nov. 22, 2012;Japanese Patent Application No. 2012-259065, filed Nov. 27, 2012;Japanese Patent Application No. 2012-259069, filed Nov. 27, 2012;Japanese Patent Application No. 2012-259078, filed Nov. 27, 2012. Theentire disclosures of each of the above applications are incorporatedherein by reference.

FIELD

The present disclosure relates to a sealing device and a sealingstructure which serve to seal an annular gap between a shaft and a shafthole in a housing.

BACKGROUND

In an automatic transmission (AT) and a continuously variabletransmission (CVT) for automotive vehicle, in order to hold oilpressure, there is arranged a seal ring which serves to seal an annulargap between a shaft and a housing which rotate relative to each other. Aseal ring according to a conventional example will be explained whilereferring to FIG. 138 and FIG. 139. FIG. 138 is a schematic crosssectional view showing a state in which oil pressure is not held in theseal ring according to the conventional example. FIG. 139 is a schematiccross sectional view showing a state in which oil pressure is held inthe seal ring according to the conventional example. A seal ring 6000according to the conventional example is fitted in an annular groove4100 formed in an outer periphery of a shaft 4000. And, the seal ring6000 seals an annular gap between a shaft hole in a housing 5000 and theshaft 4000 by making sliding contact with an inner peripheral surface ofthe shaft hole in the housing 5000 through which the shaft 4000 isinserted, and with a side wall surface of the annular groove 4100,respectively.

The seal ring 6000 used for the above-mentioned usage is required tomake sliding torque sufficiently low. For that reason, the peripherallength of an outer peripheral surface of the seal ring 6000 is madeshorter than the peripheral length of the inner peripheral surface ofthe shaft hole in the housing 5000. In this manner, the seal ring 6000is constructed such that it does not have a tightening margin withrespect to the inner peripheral surface of the shaft hole. Then, in astate where an engine of an automotive vehicle is started to operate andthe oil pressure is high, the seal ring 6000 is expanded in its diameterdue to the oil pressure, so that it makes intimate contact with theinner peripheral surface of the shaft hole and the side wall surface ofthe annular groove 4100. As a result of this, a function to hold the oilpressure is exhibited to a sufficient extent (refer to FIG. 139).

In contrast to this, in a state where the oil pressure is not applieddue to stoppage of the engine, the seal ring 6000 is in a state apart orseparated from the inner peripheral surface of the shaft hole or sidewall surfaces of the annular groove 4100 (refer to FIG. 138). For thatreason, in the state where the oil pressure is not applied, the sealring 6000 does not exhibit a sealing function. Accordingly, in aconstruction in which transmission control is carried out by means ofoil pressure fed by a hydraulic pump, as in the case of an AT or a CVT,the oil having been sealed by the seal ring 6000 will return to an oilpan in an unloaded condition in which the hydraulic pump is stopped (forexample, at the time of idling stop). As a result of this, the oil inthe vicinity of the seal ring 6000 will be lost. Thus, when the engineis started (restarted) from this state, there will be no oil in thevicinity of the seal ring 6000, and engine operation will be started ina state where there is no lubrication. For that reason, there is aproblem that responsiveness and operability are bad.

PRIOR ART REFERENCES Patent Documents

[First Patent Document] Japanese patent No. 4665046

[Second Patent Document] Japanese patent application laid-open No.2011-144847

[Third Patent Document] Japanese patent application laid-open No.2010-265937

SUMMARY Problem to be Solved by the Disclosure

An object of the present disclosure is to provide a sealing device and asealing structure which are capable of exhibiting a sealing functioneven in a state where fluid pressure is low or in a state where there isno fluid pressure, while suppressing sliding torque to a low level.

Means for Solving the Problem

In order to solve the above-mentioned problem, the present disclosureadopts the following means.

That is, a sealing device of the present disclosure, which is fittedinto an annular groove formed in an outer periphery of a shaft so as toseal an annular gap between said shaft and a housing which rotaterelative to each other, thereby to hold a fluid pressure in a region tobe sealed which is constructed such that the fluid pressure thereinchanges comprising: an outer peripheral ring made of resin that is inintimate contact with a side wall surface of said annular groove at alow pressure side thereof, and slides with respect to an innerperipheral surface of a shaft hole in said housing through which saidshaft is inserted; and an inner peripheral ring made of a rubber-likeelastic body that is in intimate contact with an inner peripheralsurface of said outer peripheral ring and a groove bottom surface ofsaid annular groove, respectively, thereby to push said outer peripheralring toward an outer peripheral surface side thereof; wherein said outerperipheral ring has a concave portion formed on its outer peripheralsurface to extend from an end of a high pressure side to a positionwhich does not arrive at an end of a low pressure side, so as tointroduce fluid thereinto from the high pressure side.

Here, note that in the present disclosure, the “high pressure side”means a side at which pressure is higher than at the other side at thetime when a differential pressure has occurred on opposite sides of thesealing device, and the “low pressure side” means a side at whichpressure is lower than at the other side at the time when a differentialpressure has occurred on opposite sides of the sealing device.

According to the sealing device of the present disclosure, the outerperipheral ring is pushed toward the outer peripheral surface sidethereof by means of the inner peripheral ring. For that reason, even ina state where the fluid pressure does not act (a differential pressurehas not occurred), or in a state where the fluid pressure does notsubstantially act (a differential pressure has not substantiallyoccurred), the outer peripheral ring will be in a state of being incontact with the inner peripheral surface of the shaft hole in thehousing, so that a sealing function thereof can be exhibited.Accordingly, the fluid pressure can be made to be held from immediatelyafter the fluid pressure in the region to be sealed begins to increase.In addition, the concave portion is formed on the outer peripheralsurface of the outer peripheral ring, so that fluid can be introducedinto this concave portion from the high pressure side. For that reason,even if the fluid pressure becomes higher, the fluid pressure actstoward the inner peripheral surface side of the outer peripheral ring ina region in which the concave portion is formed. Accordingly, anincrease in pressure toward the outer peripheral surface by means of theouter peripheral ring accompanying the increase in the fluid pressurecan be suppressed, thus making it possible to suppress sliding torque toa low level.

Effect of the Disclosure

As described above, according to the present disclosure, it is possibleto exhibit a sealing function even in a state where fluid pressure islow or in a state where there is no fluid pressure, while suppressingsliding torque to a low level.

DRAWINGS

FIG. 1 is a partially broken cross sectional view of a sealing deviceaccording to an embodiment of the present disclosure.

FIG. 2 is a view of an outer peripheral ring seen from an outerperipheral surface side thereof according to the embodiment of thepresent disclosure.

FIG. 3 is a side view of the outer peripheral ring according to theembodiment of the present disclosure.

FIG. 4 is a partially broken perspective view of the outer peripheralring according to the embodiment of the present disclosure.

FIG. 5 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the embodiment of the presentdisclosure.

FIG. 6 is a schematic cross sectional view showing a high pressure statein the sealing device according to the embodiment of the presentdisclosure.

FIG. 7 is a partially broken cross sectional view of a sealing deviceaccording to a first reference example of the present disclosure.

FIG. 8 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the first reference example of thepresent disclosure.

FIG. 9 is a schematic cross sectional view showing a high pressure statein the sealing device according to the first reference example of thepresent disclosure.

FIG. 10 is a partially broken cross sectional view of a sealing deviceaccording to a second reference example of the present disclosure.

FIG. 11 is a partially broken perspective view of an outer peripheralring according to the second reference example of the presentdisclosure.

FIG. 12 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the second reference example of thepresent disclosure.

FIG. 13 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the second reference example ofthe present disclosure.

FIG. 14 is a partially broken cross sectional view of a sealing deviceaccording to a third reference example of the present disclosure.

FIG. 15 is a side view of an outer peripheral ring (a side view seenfrom a low pressure side) according to the third reference example ofthe present disclosure.

FIG. 16 is a partially broken perspective view of an outer peripheralring according to the third reference example of the present disclosure.

FIG. 17 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the third reference example of thepresent disclosure.

FIG. 18 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the third reference example ofthe present disclosure.

FIG. 19 is a partially broken cross sectional view of a sealing deviceaccording to a first practical example of the present disclosure.

FIG. 20 is a view of an outer peripheral ring seen from an outerperipheral surface side thereof according to the first practical exampleof the present disclosure.

FIG. 21 is a side view of the outer peripheral ring according to thefirst practical example of the present disclosure.

FIG. 22 is a partially broken perspective view of the outer peripheralring according to the first practical example of the present disclosure.

FIG. 23 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the first practical example of thepresent disclosure.

FIG. 24 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the first practical example of thepresent disclosure.

FIG. 25 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the first practical example ofthe present disclosure.

FIG. 26 is a part of an external view of an outer peripheral ringaccording to a first modification of the first practical example of thepresent disclosure.

FIG. 27 is a part of an external view of an outer peripheral ringaccording to a second modification of the first practical example of thepresent disclosure.

FIG. 28 is a part of an external view of an outer peripheral ringaccording to a third modification of the first practical example of thepresent disclosure.

FIG. 29 is a partially broken cross sectional view of a sealing deviceaccording to a second practical example of the present disclosure.

FIG. 30 is a part of a view of an outer peripheral ring seen from anouter peripheral surface side thereof according to the second practicalexample of the present disclosure.

FIG. 31 is a side view of the outer peripheral ring according to thesecond practical example of the present disclosure.

FIG. 32 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the second practical example of thepresent disclosure.

FIG. 33 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the second practical example of thepresent disclosure.

FIG. 34 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the second practical example of thepresent disclosure.

FIG. 35 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the second practical example ofthe present disclosure.

FIG. 36 is a part of a view of an outer peripheral ring seen from anouter peripheral surface side thereof according to a first modificationof the second practical example of the present disclosure.

FIG. 37 is a part of a view of an outer peripheral ring seen from anouter peripheral surface side thereof according to a second modificationof the second practical example of the present disclosure.

FIG. 38 is a partially broken cross sectional view of a sealing deviceaccording to a third practical example of the present disclosure.

FIG. 39 is a side view of an outer peripheral ring according to thethird practical example of the present disclosure.

FIG. 40 is a partially broken perspective view of the outer peripheralring according to the third practical example of the present disclosure.

FIG. 41 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the third practical example of thepresent disclosure.

FIG. 42 is a partially broken perspective view of the outer peripheralring according to the third practical example of the present disclosure.

FIG. 43 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the third practical example ofthe present disclosure.

FIG. 44 is a partially broken cross sectional view of a sealing deviceaccording to a fourth practical example of the present disclosure.

FIG. 45 is a side view of an outer peripheral ring according to thefourth practical example of the present disclosure.

FIG. 46 is a partially broken perspective view of the outer peripheralring according to the fourth practical example of the presentdisclosure.

FIG. 47 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the fourth practical example of thepresent disclosure.

FIG. 48 is a partially broken perspective view of the outer peripheralring according to the fourth practical example of the presentdisclosure.

FIG. 49 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the fourth practical example ofthe present disclosure.

FIG. 50 is a partially broken cross sectional view of a sealing deviceaccording to a fourth reference example of the present disclosure.

FIG. 51 is a side view of an outer peripheral ring according to thefourth reference example of the present disclosure.

FIG. 52 is a partially broken perspective view of the outer peripheralring according to the fourth reference example of the presentdisclosure.

FIG. 53 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the fourth reference example of thepresent disclosure.

FIG. 54 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the fourth reference example ofthe present disclosure.

FIG. 55 is a schematic cross sectional view showing an unloaded state ina sealing device according to a fifth reference example of the presentdisclosure.

FIG. 56 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the fifth reference example ofthe present disclosure.

FIG. 57 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the fifth reference example ofthe present disclosure.

FIG. 58 is a part of a view of a position limiting ring seen from anouter peripheral surface side thereof according to the fifth referenceexample of the present disclosure.

FIG. 59 is a cross sectional view of the position limiting ringaccording to the fifth reference example of the present disclosure.

FIG. 60 is a schematic cross sectional view showing an unloaded state ina sealing device according to a sixth reference example of the presentdisclosure.

FIG. 61 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the sixth reference example ofthe present disclosure.

FIG. 62 is a schematic cross sectional view showing an unloaded state ina sealing device according to a seventh reference example of the presentdisclosure.

FIG. 63 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the seventh reference exampleof the present disclosure.

FIG. 64 is a schematic cross sectional view showing an unloaded state ina sealing device according to an eighth reference example of the presentdisclosure.

FIG. 65 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the eighth reference example ofthe present disclosure.

FIG. 66 is a partially broken cross sectional view of a sealing deviceaccording to a ninth reference example of the present disclosure.

FIG. 67 is a view of an outer peripheral ring seen from an outerperipheral surface side thereof according to the ninth reference exampleof the present disclosure.

FIG. 68 is a side view of the outer peripheral ring (a side view seenfrom a low pressure side) according to the ninth reference example ofthe present disclosure.

FIG. 69 is a schematic cross sectional view showing an unloaded state ina sealing structure according to the ninth reference example of thepresent disclosure.

FIG. 70 is a schematic cross sectional view showing a high pressurestate in the sealing structure according to the ninth reference exampleof the present disclosure.

FIG. 71 is a partially broken cross sectional view of a sealing deviceaccording to a tenth reference example of the present disclosure.

FIG. 72 is a side view of an outer peripheral ring according to thetenth reference example of the present disclosure.

FIG. 73 is a partially broken perspective view of the outer peripheralring according to the tenth reference example of the present disclosure.

FIG. 74 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the tenth reference example of thepresent disclosure.

FIG. 75 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the tenth reference example ofthe present disclosure.

FIG. 76 is a partially broken cross sectional view of a sealing deviceaccording to an eleventh reference example of the present disclosure.

FIG. 77 is a view of an outer peripheral ring seen from an outerperipheral surface side thereof according to the eleventh referenceexample of the present disclosure.

FIG. 78 is a side view of the outer peripheral ring according to theeleventh reference example of the present disclosure.

FIG. 79 is a partially broken perspective view of the outer peripheralring according to the eleventh reference example of the presentdisclosure.

FIG. 80 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the eleventh reference example of thepresent disclosure.

FIG. 81 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the eleventh reference exampleof the present disclosure.

FIG. 82 is a schematic cross sectional view showing a high pressurestate in the sealing device and a state where the outer peripheral ringis fitted or mounted in an opposite direction according to the eleventhreference example of the present disclosure.

FIG. 83 is a partially broken cross sectional view of a sealing deviceaccording to a twelfth reference example of the present disclosure.

FIG. 84 is a view of an outer peripheral ring seen from an outerperipheral surface side thereof according to the twelfth referenceexample of the present disclosure.

FIG. 85 is a side view of the outer peripheral ring according to thetwelfth reference example of the present disclosure.

FIG. 86 is a partially broken perspective view of the outer peripheralring according to the twelfth reference example of the presentdisclosure.

FIG. 87 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the twelfth reference example of thepresent disclosure.

FIG. 88 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the twelfth reference exampleof the present disclosure.

FIG. 89 is an explanatory view showing a high pressure state in thesealing device and a state where the outer peripheral ring is fitted ormounted in a normal direction according to the twelfth reference exampleof the present disclosure.

FIG. 90 is an explanatory view showing a high pressure state in thesealing device and a state where the outer peripheral ring is fitted ormounted in an opposite direction according to the twelfth referenceexample of the present disclosure.

FIG. 91 is a partially broken perspective view of the outer peripheralring according to a modification of the twelfth reference example of thepresent disclosure.

FIG. 92 is a partially broken cross sectional view of a sealing deviceaccording to a thirteenth reference example of the present disclosure.

FIG. 93 is a view of an outer peripheral ring seen from an outerperipheral surface side thereof according to the thirteenth referenceexample of the present disclosure.

FIG. 94 is a side view of the outer peripheral ring according to thethirteenth reference example of the present disclosure.

FIG. 95 is a partially broken perspective view of the outer peripheralring according to the thirteenth reference example of the presentdisclosure.

FIG. 96 is a perspective view of the vicinity of an abutment jointportion on the outer peripheral ring according to the thirteenthreference example of the present disclosure.

FIG. 97 is a perspective view of the vicinity of the abutment jointportion on the outer peripheral ring according to the thirteenthreference example of the present disclosure.

FIG. 98 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the thirteenth reference example of thepresent disclosure.

FIG. 99 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the thirteenth referenceexample of the present disclosure.

FIG. 100 is an explanatory view showing a high pressure state in thesealing device and a state where the outer peripheral ring is fitted ormounted in a normal direction according to the thirteenth referenceexample of the present disclosure.

FIG. 101 is an explanatory view showing a high pressure state in thesealing device and a state where the outer peripheral ring is fitted ormounted in an opposite direction according to the thirteenth referenceexample of the present disclosure.

FIG. 102 is a perspective view of the vicinity of an abutment jointportion on an outer peripheral ring according to a modification of thethirteenth reference example of the present disclosure.

FIG. 103 is a part of a view seen from an outer peripheral surface side,showing a state where a sealing device according to a fourteenthreference example of the present disclosure is mounted or fitted in anannular groove.

FIG. 104 is a schematic cross sectional view showing a state where thesealing device according to the fourteenth reference example of thepresent disclosure is mounted or fitted in the annular groove.

FIG. 105 is a part of a view seen from an outer peripheral surface side,showing a state where a sealing device according to a fifteenthreference example of the present disclosure is mounted or fitted in anannular groove.

FIG. 106 is a schematic cross sectional view showing a state where thesealing device according to the fifteenth reference example of thepresent disclosure is mounted or fitted in the annular groove.

FIG. 107 is a schematic cross sectional view showing a state where thesealing device according to the fifteenth reference example of thepresent disclosure is mounted or fitted in the annular groove.

FIG. 108 is a schematic cross sectional view showing a state where thesealing device according to the fifteenth reference example of thepresent disclosure is mounted or fitted in the annular groove.

FIG. 109 is a part of a view seen from an outer peripheral surface side,showing a state where a sealing device according to a sixteenthreference example of the present disclosure is mounted or fitted in anannular groove.

FIG. 110 is a schematic cross sectional view showing a state where thesealing device according to the sixteenth reference example of thepresent disclosure is mounted or fitted in the annular groove.

FIG. 111 is a part of a view seen from an outer peripheral surface side,showing a state where a sealing device according to a seventeenthreference example of the present disclosure is mounted or fitted in anannular groove.

FIG. 112 is a schematic cross sectional view showing a state where thesealing device according to the seventeenth reference example of thepresent disclosure is mounted or fitted in the annular groove.

FIG. 113 is a partially broken cross sectional view of a sealing deviceaccording to an eighteenth reference example of the present disclosure.

FIG. 114 is a view of an outer peripheral ring seen from an outerperipheral surface side thereof according to the eighteenth referenceexample of the present disclosure.

FIG. 115 is a side view of the outer peripheral ring according to theeighteenth reference example of the present disclosure.

FIG. 116 is a schematic cross sectional view showing an unloaded statein the sealing device according to the eighteenth reference example ofthe present disclosure.

FIG. 117 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the eighteenth referenceexample of the present disclosure.

FIG. 118 is a schematic cross sectional view showing a situation when ashaft is fitted into a shaft hole in a housing in a state where thesealing device according to the eighteenth reference example of thepresent disclosure is fitted or mounted in an opposite direction.

FIG. 119 is a schematic cross sectional view showing an unloaded statein a sealing device according to a nineteenth reference example of thepresent disclosure.

FIG. 120 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the nineteenth referenceexample of the present disclosure.

FIG. 121 is a schematic cross sectional view showing an unloaded statein a sealing device according to a twentieth reference example of thepresent disclosure.

FIG. 122 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the twentieth reference exampleof the present disclosure.

FIG. 123 is a schematic cross sectional view showing an unloaded statein a sealing device according to a twenty-first reference example of thepresent disclosure.

FIG. 124 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the twenty-first referenceexample of the present disclosure.

FIG. 125 is a schematic cross sectional view showing an unloaded statein a sealing device according to a twenty-second reference example ofthe present disclosure.

FIG. 126 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the twenty-second referenceexample of the present disclosure.

FIG. 127 is a schematic cross sectional view showing a high pressurestate in a sealing device according to a twenty-third reference exampleof the present disclosure.

FIG. 128 is a schematic cross sectional view showing a high pressurestate in a sealing device according to a twenty-fourth reference exampleof the present disclosure.

FIG. 129 is a partially broken perspective view of an outer peripheralring according to the twenty-fourth reference example of the presentdisclosure.

FIG. 130 is a schematic cross sectional view showing a high pressurestate in a sealing device according to a twenty-fifth reference exampleof the present disclosure.

FIG. 131 is a schematic cross sectional view showing a high pressurestate in a sealing device according to a twenty-sixth reference exampleof the present disclosure.

FIG. 132 is a schematic cross sectional view showing a high pressurestate in a sealing device according to a twenty-seventh referenceexample of the present disclosure.

FIG. 133 is a schematic cross sectional view showing a high pressurestate in a sealing device according to a twenty-eighth reference exampleof the present disclosure.

FIG. 134 is a schematic cross sectional view showing a high pressurestate in a sealing device according to a twenty-ninth reference exampleof the present disclosure.

FIG. 135 is a schematic cross sectional view showing a high pressurestate in a sealing device according to a thirtieth reference example ofthe present disclosure.

FIG. 136 is a perspective view showing a part of an outer peripheralring according to a thirty-first reference example of the presentdisclosure.

FIG. 137 is a part of a side view of the outer peripheral ring accordingto the thirty-first reference example of the present disclosure.

FIG. 138 is a schematic cross sectional view showing a state where oilpressure is not held in a seal ring according to a conventional example.

FIG. 139 is a schematic cross sectional view showing a state where oilpressure is held in the seal ring according to the conventional example.

DETAILED DESCRIPTION

Hereinafter, modes for carrying out the present disclosure will bedescribed in detail by way of example based on a preferred embodimentand practical examples thereof with reference to the accompanyingdrawings. However, the dimensions, materials, shapes, relativearrangements and so on of component parts described in the embodimentand practical examples are not intended to limit the scope of thepresent disclosure to these alone in particular as long as there are nospecific statements. Here, note that sealing devices according to thepresent embodiment and practical examples are used for the use orpurpose of sealing an annular gap between a shaft and a housing whichrotate relative to each other in order to hold oil pressure inspeed-change gears or transmissions for automotive vehicles, such as AT,CVT, etc. In addition, in the following description, a “high pressureside” means a side at which pressure is higher than at the other side atthe time when a differential pressure has occurred on opposite sides ofa sealing device, and a “low pressure side” means a side at whichpressure is lower than at the other side at the time when a differentialpressure has occurred on the opposite sides of the sealing device.

Embodiment

Hereinafter, a sealing device and a sealing structure according to anembodiment of the present disclosure will be explained while referringto FIG. 1 through FIG. 6.

<Construction of the Sealing Device and the Sealing Structure>

The construction of the sealing device and the sealing structureaccording to the embodiment of the present disclosure will be explained,while referring in particular to FIG. 1, FIG. 5 and FIG. 6. The sealingdevice 1000 according to the present embodiment is mounted or fitted inan annular groove 4100 formed in an outer periphery of a shaft 4000.Then, the sealing device 1000 serves to seal an annular gap between theshaft 4000 and a housing 5000 (an inner peripheral surface of a shafthole in the housing 5000 through which the shaft 4000 is inserted) whichrotate relative to each other. As a result of this, the sealing device1000 holds fluid pressure in a region to be sealed which is constructedin such a manner that the fluid pressure (oil or hydraulic pressure inthis embodiment) can change. Here, in this embodiment, it is constructedsuch that fluid pressure in a region at the right side in FIG. 5 andFIG. 6 can change, and the sealing device 1000 bears the role of holdingthe fluid pressure in the region to be sealed at the right side in thesefigures. Here, note that in a state where an engine of an automotivevehicle has been stopped, the fluid pressure in the region to be sealedis low and the engine is in an unloaded state, whereas when the engineis started, the fluid pressure in the region to be sealed will becomehigh.

Then, the sealing device 1000 according to this embodiment is composedof an outer peripheral ring 2000 made of resin, and an inner peripheralring 3000 made of a rubber-like elastic body. As preferable examples ofa material for the outer peripheral ring 2000, there can be mentionedpolyether ether ketone (PEEK), polyphenylene sulfide (PPS), andpolytetrafluoroethylene (PTFE). In addition, as preferable examples of amaterial for the inner peripheral ring 3000, there can be mentionedacrylic rubber (ACM), fluororubber (FKM), and hydrogenated nitrilerubber (HNBR). In FIG. 1, FIG. 5 and FIG. 6, the inner peripheral ring3000 is shown in a simplified manner.

In addition, it is constructed such that in a state where the outerperipheral ring 2000 and the inner peripheral ring 3000 are combined orassembled together, a peripheral length of an outer peripheral surfaceof the outer peripheral ring 2000 becomes longer than a peripherallength of an inner peripheral surface of the shaft hole in the housing5000. Here, note that, for the outer peripheral ring 2000 as a single orseparate member, the peripheral length of the outer peripheral surfacethereof is made shorter than the peripheral length of the innerperipheral surface of the shaft hole in the housing 5000. In otherwords, the outer peripheral ring 2000 as a single member is constructedsuch that it does not have a tightening margin with respect to the innerperipheral surface of the shaft hole. Accordingly, if the outerperipheral ring 2000 is made in a state where the inner peripheral ring3000 is not mounted or fitted therein and an external force does not actthereon, the outer peripheral surface of the outer peripheral ring 2000will not be in contact with the inner peripheral surface of the shafthole in the housing 5000.

<Outer Peripheral Ring>

In particular, the outer peripheral ring 2000 according to theembodiment of the present disclosure will be explained in further detailwhile referring to FIG. 1 through FIG. 4. An abutment joint portion 2100is formed on the outer peripheral ring 2000 at one place in acircumferential direction thereof. In addition, the outer peripheralring 2000 is formed on its outer peripheral surface with a concaveportion 2220 for introducing fluid. Here, note that the outer peripheralring 2000 according to this embodiment is constructed such that theabutment joint portion 2100 and the concave portion 2220 as mentionedabove are formed on an annular member of which the cross section isrectangular. However, this is only an explanation of the shape thereof,but does not necessarily mean that an annular member of a rectangularcross section is used as a material, and processing to form the abutmentjoint portion 2100 and the concave portion 2220 is applied to thismaterial. Of course, after an annular member of a rectangular crosssection has been molded or formed, the abutment joint portion 2100 andthe concave portion 2220 can also be obtained by means of cutting work.However, for example, after molding or forming a member which has theabutment joint portion 2100 in advance, the concave portion 2220 may beobtained by means of cutting work. In this manner, the method ofproduction thereof is not limited in particular.

The abutment joint portion 2100 adopts a so-called special step cutwhich is formed by being cut in a stepwise shape even when seen from anyof an outer peripheral surface side and opposite side wall surface sidesthereof. As a result of this, in the outer peripheral ring 2000, a firstfitting convex portion 2111 and a first fitting concave portion 2121 areformed at one outer peripheral side of a cut portion, and a secondfitting concave portion 2122 into which the first fitting convex portion2111 fits, and a second fitting convex portion 2112 which fits into thefirst fitting concave portion 2121, are formed at the other outerperipheral side. A special step cut has a characteristic of maintainingstable sealing performance even if the peripheral length of the outerperipheral ring 2000 is changed due to thermal expansion andcontraction. Such a special step cut is a well-known technique, so adetailed explanation thereof is omitted.

Here, a case of the special step cut has been shown as an example of theabutment joint portion 2100. However, for the abutment joint portion2100, there can be adopted a straight cut, a bias cut, another step cut,and so on, including but not limited to this. Here, note that the stepcut is of a stepwise cut structure even if seen from any of an outerperipheral surface side and an inner peripheral surface side. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100.

The concave portion 2220 is formed substantially over the entireperiphery except for the vicinity of the abutment joint portion 2100. Inaddition, this concave portion 2220 is formed in such a manner that itextends from one end (i.e., a high pressure side (H) as referred tolater) of the outer peripheral ring 2000 to a location not reaching theother end thereof (i.e., a low pressure side (L) as referred to later).More specifically, this concave portion 2220 is formed so as to extendto the vicinity of the other end of the outer peripheral ring 2000.Here, note that a bottom surface of the concave portion 2220 is composedof a surface which is concentric with an inner peripheral surface of theouter peripheral ring 2000. Hereinafter, a portion of the outerperipheral surface side of the outer peripheral ring 2000 in which theconcave portion 2220 is not formed at the other side (the low pressureside (L)) is referred to as a low pressure side convex portion 2210.Here, note that the shallower the depth of the concave portion 2220, thehigher becomes the rigidity of the portion of the outer peripheral ring2000 in which the low pressure side convex portion 2210 is formed. Onthe other hand, the low pressure side convex portion 2210 is worn outdue to the relative sliding movement thereof, so the depth of theconcave portion 2220 becomes shallower as the time elapses. For thatreason, when the depth of the concave portion 2220 becomes too muchshallow, it will become impossible to introduce fluid therein.Accordingly, it is desirable to set an initial depth of the concaveportion 2220 by taking into consideration both the above-mentionedrigidity and the maintenance of introduction of fluid even if the wearprogresses with the lapse of time. For example, in cases where thethickness of the outer peripheral ring 2000 is 1.7 mm, it is preferableto set the depth of the concave portion 2220 to be equal to or more thanabout 0.1 mm and equal to or less than about 0.3 mm.

In addition, with respect to the width (width in an axial direction) ofthe concave portion 2220, the wider the width of the concave portion2220, the narrower becomes the width of the low pressure side convexportion 2210. The narrower becomes this width, the more the torque canbe reduced, but if the width is made too much narrow, sealing efficiencyand durability will become low. Accordingly, it is desirable to narrowthe width concerned as much as possible according to service conditions,etc., to such an extent that sealing efficiency and durability can bemaintained. Here, note that for example, in cases where the entirelength of the width (width in the axial direction) of the outerperipheral ring 2000 is 1.9 mm, it is preferable to set the width of thelow pressure side convex portion 2210 to be equal to or more than about0.3 mm and equal to or less than about 0.7 mm.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis embodiment of the present disclosure will be explained, whilereferring in particular to FIG. 5 and FIG. 6. FIG. 5 shows an unloaded(or low load) state in which the engine is stopped, and there does notexist a differential pressure (or there exists substantially nodifferential pressure) between right-hand side region of the sealingdevice 1000 and left-hand side region of the sealing device 1000. FIG. 6shows a state in which the engine is operated, and the fluid pressure inthe right-hand side region of the sealing device 1000 has become higherin comparison with that in the left-hand side region of the sealingdevice 1000.

In a state where the sealing device 1000 is fitted in the annular groove4100, the inner peripheral ring 3000 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3000 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portion 2220 (i.e., the low pressure side convexportion 2210 and a portion of the outer peripheral ring 2000 in thevicinity of the abutment joint portion 2100 in which the concave portion2220 is not formed) maintain a state in which they are in contact withthe inner peripheral surface of the shaft hole in the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed to thelow pressure side (L) by means of the fluid pressure from the highpressure side (H), so that it becomes a state of being in intimatecontact with the side wall surface of the annular groove 4100 at the lowpressure side (L), as shown in FIG. 6. Here, note that it is needless tosay that the outer peripheral ring 2000 maintains the state of being incontact (sliding) with the inner peripheral surface of the shaft hole inthe housing 5000. In addition, with respect to the inner peripheral ring3000, too, it also becomes a state where it is in intimate contact withthe side wall surface of the annular groove 4100 at the low pressureside (L).

<Advantages of the Sealing Device and the Sealing Structure According tothis Embodiment>

According to the sealing device 1000 and sealing structure providedtherewith according to this embodiment of the present disclosure, theouter peripheral ring 2000 is pushed toward the outer peripheral surfaceside thereof by mean of the inner peripheral ring 3000. For that reason,even in a state where the fluid pressure does not act (a differentialpressure has not occurred), or in a state where the fluid pressure doesnot substantially act (a differential pressure has not substantiallyoccurred), the outer peripheral ring 2000 becomes the state of being incontact with the inner peripheral surface of the shaft hole in thehousing 5000. Here, note that an annular continuous sealing surface isformed by the outer peripheral surface of the low pressure side convexportion 2210 and that portion of the outer peripheral surface of theouter peripheral ring 2000 in which the concave portion 2220 is notformed in the vicinity of the abutment joint portion 2100.

Accordingly, the fluid pressure can be made to be held from immediatelyafter the fluid pressure in the region to be sealed begins to increase.In other words, in an engine having an idling stop function, oilpressure can be made to be held immediately after oil pressure at theside of the region to be sealed begins to increase due to starting ofthe engine by an accelerator being depressed from an engine stoppedstate.

Here, in general, in the case of a seal ring made of resin, the functionof suppressing the leakage of fluid is not exhibited so much. However,in this embodiment, the outer peripheral ring 2000 is pushed toward theouter peripheral surface side thereof by mean of the inner peripheralring. For that reason, the function of suppressing the leakage of fluidis exhibited to some extent. As a result of this, even after the actionof a pump, etc., is stopped due to stoppage of the engine, it becomespossible to maintain the state where a differential pressure hasoccurred for a while. For that reason, in the engine having an idlingstop function, in cases where the stopped state of the engine is not solong, it is possible to maintain the state where a differential pressurehas occurred. Accordingly, at the time of carrying out the restarting ofthe engine, it is possible to hold the fluid pressure in a suitablemanner from immediately after that.

In addition, the concave portion 2220 is formed on the outer peripheralsurface of the outer peripheral ring 2000, so that fluid can beintroduced into this concave portion 2220 from the high pressure side(H). For that reason, even if the fluid pressure becomes higher, thefluid pressure acts toward the inner peripheral surface side of theouter peripheral ring 2000 in a region in which the concave portion 2220is formed. Here, in this embodiment, the bottom surface of the concaveportion 2220 is composed of a surface which is concentric with the innerperipheral surface of the outer peripheral ring 2000. For that reason,in the region in which the concave portion 2220 is formed, a directionin which the fluid pressure acts from the inner peripheral surface sideand a direction in which the fluid pressure acts from the outerperipheral surface side become opposite to each other. Furthermore, itis needless to say that in a region in which the outer peripheral ring2000 receives pressure from both of the inner peripheral surface sideand the outer peripheral surface side, an outside diameter of the outerperipheral ring 2000 is larger than an inside diameter thereof, andhence, an area in which the fluid pressure acts becomes wider in theouter peripheral surface side than in the inner peripheral side. Here,note that an arrow in FIG. 6 shows how the fluid pressure acts withrespect to the outer peripheral ring 2000. In this manner, in thesealing device 1000 according to this embodiment, it is possible tosuppress an increase in pressure toward the outer peripheral surface bymeans of the outer peripheral ring 2000 accompanying an increase in thefluid pressure, thus making it possible to suppress sliding torque to alow level.

Moreover, in this embodiment, the inner peripheral ring 3000 is inintimate contact with the inner peripheral surface of the outerperipheral ring 2000 and the groove bottom surface of the annular groove4100, respectively, so that it exhibits a sealing function in theseintimate contact portions thereof. For that reason, by the sealingfunction of the inner peripheral ring 3000, it is possible to suppressthe action of the fluid pressure with respect to that portion of theinner peripheral surface of the outer peripheral ring 2000 whichcorresponds to a sliding portion between the low pressure side convexportion 2210 in the outer peripheral ring 2000 and the shaft hole innerperipheral surface. In other words, as shown in FIG. 6, in the region ofthe low pressure side (L) from the intimate contact portion of the innerperipheral ring 3000, it is possible to suppress the action of the fluidpressure with respect to the inner peripheral surface of the outerperipheral ring 2000. Accordingly, even if the fluid pressure at thehigh pressure side (H) increases, it is possible to suppress an increasein the pressure to the outer peripheral surface side by the outerperipheral ring 2000 in an effective manner.

Further, in this embodiment, the concave portion 2220 is formed so as toextend from an end of the high pressure side (H) to the vicinity of anend of the low pressure side (L) and over the entire periphery of theouter peripheral ring 2000 except for the vicinity of the abutment jointportion 2100. Thus, in this embodiment, due to the fact that the concaveportion 2220 is formed over a wide range of the outer peripheral surfaceof the outer peripheral ring 2000, it is possible to make the slidingarea between the outer peripheral ring 2000 and the inner peripheralsurface of the shaft hole in the housing 5000 as narrow as possible. Asa result, the sliding torque can be reduced very much. Here, note thatthe sliding area between the outer peripheral ring 2000 and the innerperipheral surface of the shaft hole in the housing 5000 is sufficientlynarrower than the area of intimate contact between the outer peripheralring 2000 and the side wall surface of the annular groove 4100 at thelow pressure side (L). With this, it is possible to suppress the outerperipheral ring 2000 from sliding with respect to the side wall surfaceof the annular groove 4100 at the low pressure side (L). Accordingly,the outer peripheral ring 2000 according to this embodiment slides atthe outer peripheral surface side. For that reason, in comparison withthe case of a seal ring which slides with respect to the side wallsurface of the annular groove, it becomes easy for a lubricating film(here an oil film) of the fluid being sealed to be formed, so that thesliding torque can be reduced to a further extent.

In this manner, the generation of heat due to sliding can be suppressedby being able to achieve the reduction of the sliding torque.Accordingly, it becomes possible to use the sealing device 1000according to this embodiment in a suitable manner even under ahigh-speed high-pressure environmental condition.

Hereinafter, some more specific examples will be described. Here, notethat in the following individual reference examples and individualpractical examples, the use of sealing devices, and materials for theirouter peripheral rings and inner peripheral rings are as described inthe above-mentioned embodiment. Accordingly, in the following individualreference examples and individual practical examples, the explanation ofthese will be omitted as the case may be.

First Reference Example

Hereinafter, a sealing device and a sealing structure according to afirst reference example of the present disclosure will be explainedwhile referring to FIG. 7 through FIG. 9. In this reference example, aconstruction is shown in which an O ring is adopted as the innerperipheral ring in the above-mentioned embodiment. The otherconstruction and operation of this example are the same as those in theabove-mentioned embodiment, and hence, the same parts as those of theabove-mentioned embodiment are denoted by the same reference numeralsand characters, and the explanation thereof is omitted as the case maybe.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this reference example is a so-called O ring having acircular cross sectional shape.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

The outer peripheral ring 2000 is the same as explained in theabove-mentioned embodiment, and so, the detailed explanation thereof isomitted. In addition, a mechanism at the time of use of the sealingdevice 1000, too, is the same as explained in the above-mentionedembodiment. Here, note that FIG. 8 shows an unloaded state in which anengine is stopped, and there does not exist a differential pressure (orthere exists substantially no differential pressure) between right-handside region of the sealing device 1000 and left-hand side region of thesealing device 1000. FIG. 9 shows a state in which the engine isoperated, and fluid pressure in the right-hand side region of thesealing device 1000 has become higher in comparison with that in theleft-hand side region of the sealing device 1000. The advantage of thesealing device 1000 and the sealing structure provided with this sealingdevice according to this reference example are the same as explained inthe above-mentioned embodiment.

Second Reference Example Summary

A sealing device according to a second reference example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is fitted in a mounting groove formedin an inner peripheral surface of said outer peripheral ring, and is inintimate contact with a groove bottom surface of said mounting grooveand a groove bottom surface of said annular groove, respectively,thereby to push said outer peripheral ring toward an outer peripheralsurface side thereof; wherein said outer peripheral ring is formed onits outer peripheral surface with a concave portion which extends froman end of a high pressure side to a position which does not arrive at anend of a low pressure side, so as to introduce fluid thereinto from thehigh pressure side.

According to the sealing device according to this second referenceexample, the following advantages are achieved in comparison with thesealing device explained in the above-mentioned embodiment. That is, inthis reference example, the inner peripheral ring is fitted into themounting groove formed in the inner peripheral surface of the outerperipheral ring, so that the position and posture of the innerperipheral ring with respect to the outer peripheral ring arestabilized. Accordingly, the outer peripheral ring can be pushed towardthe outer peripheral surface side in a stable manner. In addition, evenif fluid pressure acts on the inner and outer peripheral rings, it ispossible to suppress the inner peripheral ring from being twisted.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thesecond reference example of the present disclosure will be explainedmore specifically, while referring to FIG. 10 through FIG. 13. Here,note that the basic construction of this example is the same as that ofthe above-mentioned embodiment and the above-mentioned first referenceexample, so the same parts are denoted by the same reference numeralsand characters, and the explanation thereof is omitted.

A sealing device 1000 according to this second reference example iscomposed of an outer peripheral ring 2000 made of resin, and an innerperipheral ring 3100 made of a rubber-like elastic body. The innerperipheral ring 3100 according to this second reference example is aso-called O ring having a circular cross sectional shape. However, theinner peripheral ring 3100 is not limited to the O ring, but as suchthere can be adopted other seal ring such as a rectangular or polygonalring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this second referenceexample of the present disclosure will be explained in further detailwhile referring in particular to FIG. 10 and FIG. 11. An abutment jointportion 2100 is formed on the outer peripheral ring 2000 at one place ina circumferential direction thereof. In addition, the outer peripheralring 2000 is formed on its outer peripheral surface with a concaveportion 2220 for introducing fluid. Further, the outer peripheral ring2000 is also formed on its inner peripheral surface with a mountinggroove 2321 for mounting the inner peripheral ring 3100 thereon.

Here, note that the outer peripheral ring 2000 according to this secondreference example is constructed such that the abutment joint portion2100, the concave portion 2220 and the mounting groove 2321 as mentionedabove are formed on an annular member of which the cross section isrectangular. However, this is only an explanation of the shape thereof,but does not necessarily mean that an annular member of a rectangularcross section is used as a material, and processing to form the abutmentjoint portion 2100, the concave portion 2220 and the mounting groove2321 is applied to this material. Of course, after an annular member ofa rectangular cross section has been molded or formed, the abutmentjoint portion 2100, the concave portion 2220 and the mounting groove2321 can also be obtained by means of cutting work. However, forexample, after molding or forming a member which has the abutment jointportion 2100 in advance, the concave portion 2220 and the mountinggroove 2321 may be obtained by means of cutting work. In this manner,the method of production thereof is not limited in particular.

A special step cut is used for the abutment joint portion 2100, similarto the above-mentioned embodiment. However, for the abutment jointportion 2100, there can be adopted a straight cut, a bias cut, anotherstep cut, and so on, including but not limited to this. In addition, incases where a material (e.g., PTFE, etc.) of low elasticity is adoptedas a material of the outer peripheral ring 2000, the outer peripheralring 2000 may also be endless, without forming the abutment jointportion 2100.

In this second reference example, too, the concave portion 2220 isformed over the entire periphery of the outer peripheral ring 2000except for the vicinity of the abutment joint portion 2100. Because theconcave portion 2220 is formed as explained in the above-mentionedembodiment, the detailed explanation thereof is omitted.

The mounting groove 2321 is formed over the entire periphery of theouter peripheral ring 2000 except for the abutment joint portion 2100.Here, note that in a state where a gap of a cut portion in the abutmentjoint portion 2100 is lost, the mounting groove 2321 becomes an annulargroove. In addition, with respect to the mounting groove 2321, a crosssectional shape thereof cut by a plane including an axis (a central axisof a shaft 4000) is a substantially arc shape so as to conform to theshape of the inner peripheral ring 3100. Here, note that in cases wherethe inner peripheral ring 3100 is not an O ring, that is the innerperipheral ring 3100 does not have a circular cross sectional shape, itis also necessary to conform the cross sectional shape of the mountinggroove 2321 to the cross sectional shape of the inner peripheral ring.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis second reference example will be explained, while referring inparticular to FIG. 12 and FIG. 13. FIG. 12 shows an unloaded state inwhich an engine is stopped, and there does not exist a differentialpressure (or there exists substantially no differential pressure)between right-hand side region of the sealing device 1000 and left-handside region of the sealing device 1000. FIG. 13 shows a state in whichthe engine is operated, and fluid pressure in the right-hand side regionof the sealing device 1000 has become higher in comparison with that inthe left-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in the annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis mounted or fitted in the mounting groove 2321 formed on the innerperipheral surface of the outer peripheral ring 2000. According to this,the inner peripheral ring 3100 is in intimate contact with the groovebottom surface of the mounting groove 2321 in the outer peripheral ring2000 and the groove bottom surface of the annular groove 4100,respectively. Then, the inner peripheral ring 3100 exhibits a functionof pushing the outer peripheral ring 2000 toward its outer peripheralsurface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portion 2220 (i.e., the low pressure side convexportion 2210 and a portion of the outer peripheral ring 2000 in thevicinity of the abutment joint portion 2100 in which the concave portion2220 is not formed) maintain a state in which they are in contact withthe inner peripheral surface of the shaft hole in the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed to thelow pressure side (L) by means of the fluid pressure from the highpressure side (H), so that it becomes a state of being in intimatecontact with the side wall surface of the annular groove 4100 at the lowpressure side (L), as shown in FIG. 13. Here, note that it is needlessto say that the outer peripheral ring 2000 maintains the state of beingin contact (sliding) with the inner peripheral surface of the shaft holein the housing 5000. And, with respect to the inner peripheral ring3100, it is fitted in the mounting groove 2321 in the outer peripheralring 2000, so the position and posture of the inner peripheral ring 3100with respect to the outer peripheral ring 2000 are maintained in astable state.

<Advantages of the Sealing Device and the Sealing Structure According tothis Reference Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this second reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, the innerperipheral ring 3100 is mounted or fitted in the mounting groove 2321formed in the inner peripheral surface of the outer peripheral ring2000, so that the position and posture of the inner peripheral ring 3100with respect to the outer peripheral ring 2000 are stabilized.Accordingly, the outer peripheral ring 2000 can be pushed toward theouter peripheral surface side thereof in a stable manner. In addition,even if fluid pressure acts on the outer peripheral ring 2000 (i.e.,fluid pressure varies), it is possible to suppress the inner peripheralring 3100 from being twisted.

Third Reference Example Summary

A sealing device according to a third reference example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that makes intimate contact with a side wall surface at alow pressure side in said in an annular groove and carries out slidingmovement with respect to an inner peripheral surface of a shaft hole insaid housing through which said shaft is inserted; and an innerperipheral ring made of a rubber-like elastic body that makes intimatecontact with the inner peripheral surface of said of the outerperipheral ring and a groove bottom surface of said annular groove,respectively, thereby to push said outer peripheral ring toward an outerperipheral surface side; wherein said outer peripheral ring is formed onits outer peripheral surface with a first concave portion which extendsfrom an end of a high pressure side to a position which does not arriveat an end of a low pressure side, so as to introduce fluid thereintofrom the high pressure side; and wherein said outer peripheral ring isformed on its inner peripheral surface with a second concave portion inwhich said inner peripheral ring is fitted and which extends from an endof a low pressure side to a position which does not arrive at an end ofa high pressure side, so as to limit a range of movement in an axialdirection of said inner peripheral ring.

According to the sealing device according to this third referenceexample, the following advantages are achieved in comparison with thesealing device explained in the above-mentioned embodiment. That is, inthis reference example, the inner peripheral ring is mounted or fittedin the second concave portion formed on the inner peripheral surface ofthe outer peripheral ring, so that the range of movement thereof in theaxial direction is limited. For that reason, the position and posture ofthe inner peripheral ring with respect to the outer peripheral ring arestabilized. Accordingly, the outer peripheral ring can be pushed towardthe outer peripheral surface side thereof in a stable manner. Inaddition, even if fluid pressure acts on the outer peripheral ring, itis possible to suppress the inner peripheral ring from being twisted.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thethird reference example of the present disclosure will be explained morespecifically while referring to FIG. 14 through FIG. 18. Here, note thatthe basic construction of this example is the same as that of theabove-mentioned embodiment and individual reference examples, and hence,the same component parts are denoted by the same reference numerals andcharacters, and the explanation thereof is omitted as the case may be.

A sealing device 1000 according to this third reference example iscomposed of an outer peripheral ring 2000 made of resin, and an innerperipheral ring 3100 made of a rubber-like elastic body. The innerperipheral ring 3100 according to this third reference example is aso-called O ring having a circular cross sectional shape. However, theinner peripheral ring 3100 is not limited to the O ring, but as suchthere can be adopted other seal ring such as a rectangular or polygonalring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this third reference exampleof the present disclosure will be explained in further detail whilereferring in particular to FIG. 14 through FIG. 16. An abutment jointportion 2100 is formed on the outer peripheral ring 2000 at one place ina circumferential direction thereof. In addition, the outer peripheralring 2000 is formed on its outer peripheral surface with a first concaveportion 2220 for introducing fluid. Further, the outer peripheral ring2000 is formed on its inner peripheral surface with a second concaveportion 2322 in which the inner peripheral ring 3100 is fitted.

Here, note that the outer peripheral ring 2000 according to this thirdreference example is constructed such that the abutment joint portion2100, the first concave portion 2220 and the second concave portion 2322as mentioned above are formed on an annular member of which the crosssection is rectangular. However, this is only an explanation of theshape thereof, but does not necessarily mean that an annular member of arectangular cross section is used as a material, and processing to formthe abutment joint portion 2100, the first concave portion 2220 and thesecond concave portion 2322 is applied to this material. Of course,after an annular member of a rectangular cross section has been moldedor formed, the abutment joint portion 2100, the first concave portion2220 and the second concave portion 2322 can also be obtained by meansof cutting work. However, for example, after molding or forming a memberwhich has the abutment joint portion 2100 in advance, the first concaveportion 2220 and the second concave portion 2322 may be obtained bymeans of cutting work. In this manner, the method of production thereofis not limited in particular.

A special step cut is employed for the abutment joint portion 2100,similar to the above-mentioned embodiment. However, for the abutmentjoint portion 2100, there can be adopted a straight cut, a bias cut,another step cut, and so on, including but not limited to this. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100.

In this third reference example, too, the first concave portion 2220 isformed over the entire periphery of the outer peripheral ring 2000except for the vicinity of the abutment joint portion 2100. With respectto the first concave portion 2220, it is the same as explained in theabove-mentioned embodiment (i.e., the same construction as the concaveportion 2220 in the above-mentioned embodiment), so the detailedexplanation thereof is omitted.

Also, the second concave portion 2322 is formed over the entireperiphery of the outer peripheral ring 2000 except for the abutmentjoint portion 2100. Here, note that in a state where a gap of a cutportion in the abutment joint portion 2100 is lost, the second concaveportion 2322 becomes an annular concave portion. However, in cases whereto form a concave portion in the vicinity of the abutment joint portion2100 is difficult, it is not necessary to form the concave portion inthe vicinity of the abutment joint portion 2100. This second concaveportion 2322 is formed in such a manner that it extends from one end(i.e., a low pressure side (L)) of the outer peripheral ring 2000 to alocation not reaching the other end thereof (i.e., a high pressure side(H)). Here, in the inner peripheral surface side of the outer peripheralring 2000, an annular convex portion (substantially annular convexportion) 2311, which remains in the vicinity of the other end thereofwithout the second concave portion 2322 being formed, functions as astopper which serves to restrict the axial movement of the innerperipheral ring 3100.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis third reference example will be explained, while referring inparticular to FIG. 17 and FIG. 18. FIG. 17 shows an unloaded state inwhich an engine is stopped, and there does not exist a differentialpressure (or there exists substantially no differential pressure)between right-hand side region of the sealing device 1000 and left-handside region of the sealing device 1000. FIG. 18 shows a state in whichthe engine is operated, and fluid pressure in the right-hand side regionof the sealing device 1000 has become higher in comparison with that inthe left-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in the annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis mounted or fitted in the second concave portion 2322 formed on theinner peripheral surface of the outer peripheral ring 2000. According tothis, the inner peripheral ring 3100 is in intimate contact with theinner peripheral surface of the outer peripheral ring 2000 (i.e., theinner peripheral surface of that portion in which the second concaveportion 2322 is formed) and the groove bottom surface of the annulargroove 4100, respectively. Then, the inner peripheral ring 3100 exhibitsa function of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the first concave portion 2220 (i.e., the low pressure sideconvex portion 2210 and a portion of the outer peripheral ring 2000 inthe vicinity of the abutment joint portion 2100 in which the firstconcave portion 2220 is not formed) maintain a state in which they arein contact with the inner peripheral surface of the shaft hole in thehousing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed by meansof the fluid pressure from the high pressure side (H), so that itbecomes a state of being in intimate contact with the side wall surfaceof the annular groove 4100 at the low pressure side (L), as shown inFIG. 18. Here, note that it is needless to say that the outer peripheralring 2000 maintains the state of being in contact (sliding) with theinner peripheral surface of the shaft hole in the housing 5000.

In addition, with respect to the inner peripheral ring 3100, it isfitted in the second concave portion 2322 in the outer peripheral ring2000, so that a movement thereof in the axial direction is limited. Inother words, the movement of the inner peripheral ring 3100 toward thehigh pressure side (H) is limited by the convex portion 2311 formed atthe inner peripheral surface side of the outer peripheral ring 2000. Asa result, the position and posture of the inner peripheral ring 3100with respect to the outer peripheral ring 2000 are kept in a stablestate.

<Advantages of the Sealing Device and the Sealing Structure According tothis Reference Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this third reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, the innerperipheral ring 3100 is mounted or fitted in the second concave portion2322 formed on the inner peripheral surface of the outer peripheral ring2000, so that the range of movement thereof in the axial direction islimited. As a result, the position and posture of the inner peripheralring 3100 with respect to the outer peripheral ring 2000 are stabilized.Accordingly, the outer peripheral ring 2000 can be pushed toward theouter peripheral surface side thereof in a stable manner. In addition,even if fluid pressure acts on the outer peripheral ring 2000 (i.e.,fluid pressure varies), it is possible to suppress the inner peripheralring 3100 from being twisted.

First Practical Example Summary

A sealing device according to a first practical example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that makes intimate contact with a side wall surface at alow pressure side in said in an annular groove and carries out slidingmovement with respect to an inner peripheral surface of a shaft hole insaid housing through which said shaft is inserted; and an innerperipheral ring made of a rubber-like elastic body that makes intimatecontact with the inner peripheral surface of said of the outerperipheral ring and a groove bottom surface of said annular groove,respectively, thereby to push said outer peripheral ring toward an outerperipheral surface side; wherein said outer peripheral ring is formed onits outer peripheral surface with a plurality of concave portions whichare spaced with respect to one another in a circumferential directionand which each extend from an end of a high pressure side to a positionwhich does not arrive at an end of a low pressure side, so as tointroduce fluid thereinto from the high pressure side.

According to the sealing device according to this practical example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this practicalexample, the concave portions are formed in plurality in a spaced-apartrelation with respect to one another in a circumferential direction. Forthat reason, the portions between adjacent concave portions will be in astate of contact with the inner peripheral surface of the shaft hole inthe housing, and can suppress the reduction in rigidity of the outerperipheral ring. Accordingly, it is possible to suppress the outerperipheral ring from being inclined in the annular groove, therebymaking it possible to stabilize the mounting state of the outerperipheral ring.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thefirst practical example of the present disclosure will be explained morespecifically while referring to FIG. 19 through FIG. 28. Here, note thatthe basic construction of this example is the same as that of theabove-mentioned embodiment and individual reference examples, and hence,the same component parts are denoted by the same reference numerals andcharacters, and the explanation thereof is omitted as the case may be.

A sealing device 1000 according to this practical example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this practical example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O ring, but as such there can be adopted otherseal ring such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this practical example ofthe present disclosure will be explained in further detail whilereferring in particular to FIG. 19 through FIG. 22. An abutment jointportion 2100 is formed on the outer peripheral ring 2000 at one place ina circumferential direction thereof. In addition, the outer peripheralring 2000 is formed on its outer peripheral surface with a plurality ofconcave portions 2220 which are respectively spaced from one another ina circumferential direction.

Here, note that the outer peripheral ring 2000 according to thispractical example is constructed such that the abutment joint portion2100 and the plurality of concave portions 2220 as mentioned above areformed on an annular member of which the cross section is rectangular.However, this is only an explanation of the shape thereof, but does notnecessarily mean that an annular member of a rectangular cross sectionis used as a material, and processing to form the abutment joint portion2100 and the plurality of concave portions 2220 is applied to thismaterial. Of course, after an annular member of a rectangular crosssection has been molded or formed, the abutment joint portion 2100 andthe plurality of concave portions 2220 can also be obtained by means ofcutting work. However, for example, after molding or forming a memberwhich has the abutment joint portion 2100 in advance, the plurality ofconcave portions 2220 may be obtained by means of cutting work. In thismanner, the method of production thereof is not limited in particular.

A special step cut is employed for the abutment joint portion 2100,similar to the above-mentioned embodiment. However, for the abutmentjoint portion 2100, there can be adopted a straight cut, a bias cut,another step cut, and so on, including but not limited to this. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100.

That is, in this practical example, the concave portions 2220 are formedin plurality in a spaced-apart relation with respect to one another in acircumferential direction. Here, note that in this practical example,the plurality of concave portions 2220 are arranged so as to be at equalintervals, except for the vicinity of the abutment joint portion 2100.In addition, the concave portions 2220 are constructed in such a mannerthat they each have a relatively long length in the circumferentialdirection, and the length in the circumferential direction of eachportion between the adjacent concave portions 2220 except for thevicinity of the abutment joint portion 2100 becomes shorter incomparison with the length in the circumferential direction of each ofthe adjacent concave portions 2220. Hereinafter, the portions betweenthe adjacent concave portions 2220 are each called a rib 2211. With sucha construction, the concave portions 2220 are formed over substantiallythe entire region in the circumferential direction. In other words,except for those portions in which the abutment joint portion 2100 andthe plurality of ribs 2211 each having a short length in thecircumferential direction are formed, the concave portions 2220 areformed over the entire region of the outer peripheral ring 2000 in thecircumferential direction. In addition, it is constructed such that theopposite side surfaces of each rib 2211 in this practical example arevertical from the bottom surfaces of the adjacent concave portions 2220.

In addition, the concave portions 2220 are formed in such a manner thatthey each extend from one end of the outer peripheral ring 2000 to alocation not reaching the other end thereof, similar to the case of theabove-mentioned embodiment. More specifically, the concave portions 2220are formed so as to extend to the vicinity of the other end of the outerperipheral ring 2000. Here, note that in this practical example, too,the bottom surfaces of the concave portions 2220 are composed ofsurfaces which are concentric with the inner peripheral surface of theouter peripheral ring 2000. The shallower the depth of the concaveportions 2220, the higher becomes the rigidity of those portions of theouter peripheral ring 2000 in which the ribs 2211 and low pressure sideconvex portions 2210 are formed. On the other hand, these ribs 2211 andlow pressure side convex portions 2210 are worn out due to the relativesliding movement thereof, so the depth of the concave portions 2220becomes shallower as the time elapses. For that reason, when the depthof the concave portions 2220 becomes too much shallow, it will becomeimpossible to introduce fluid therein. Accordingly, it is desirable toset an initial depth of the concave portions 2220 by taking intoconsideration both the above-mentioned rigidity and the maintenance ofintroduction of fluid even if the wear progresses with the lapse oftime. For example, in cases where the thickness of the outer peripheralring 2000 is 1.7 mm, it is preferable to set the depth of the concaveportions 2220 to be equal to or more than about 0.1 mm and equal to orless than about 0.3 mm.

Moreover, with respect to the width (width in the axial direction) ofthe concave portions 2220, the wider the width of the concave portions2220, the narrower becomes the width of the low pressure side convexportions 2210. The narrower this width becomes, the more the torque canbe reduced, but if the width is made too much narrow, sealing efficiencyand durability will become low. Accordingly, it is desirable to narrowthe width concerned as much as possible according to service conditions,etc., to such an extent that sealing efficiency and durability can bemaintained. Here, note that for example, in cases where the entirelength of the width (width in the axial direction) of the outerperipheral ring 2000 is 1.9 mm, it is preferable to set the width of thelow pressure side convex portions 2210 to be equal to or more than about0.3 mm and equal to or less than about 0.7 mm. Also, it is preferable toset the width in the circumferential direction of the ribs 2211 to beequal to or more than 0.3 mm and equal to or less than 0.7 mm.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis practical example will be explained, while referring in particularto FIG. 23 through FIG. 25. FIG. 23 and FIG. 24 each show an unloadedstate in which an engine is stopped, and there does not exist adifferential pressure (or there exists substantially no differentialpressure) between right-hand side region of the sealing device 1000 andleft-hand side region of the sealing device 1000. Here, note that FIG.23 is a schematic cross sectional view (i.e., a cross sectional viewincluding an axis of a shaft 4000) of a portion in which a concaveportion 2220 is formed in the outer peripheral ring 2000, and FIG. 24 isa schematic cross sectional view (i.e., a cross sectional view includingthe axis of the shaft 4000) of a portion in which a rib 2211 is formedin the outer peripheral ring 2000. The outer peripheral ring 2000 inFIG. 23 corresponds to an AA cross section in FIG. 21, and the outerperipheral ring 2000 in FIG. 24 corresponds to a BB cross section inFIG. 21. FIG. 25 shows a state in which the engine is operated, andfluid pressure in the right-hand side region of the sealing device 1000has become higher in comparison with that in the left-hand side regionof the sealing device 1000. Here, note that FIG. 25 is a schematic crosssectional view (i.e., a cross sectional view including the axis of theshaft 4000) of a portion in which a concave portion 2220 is formed inthe outer peripheral ring 2000. The outer peripheral ring 2000 in FIG.25 corresponds to the AA cross section in FIG. 21.

In a state where the sealing device 1000 is fitted in an annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portions 2220 (i.e., the low pressure side convexportions 2210, the ribs 2211 and a portion of the outer peripheral ring2000 in the vicinity of the abutment joint portion 2100 in which aconcave portion 2220 is not formed) maintain a state in which they arein contact with the inner peripheral surface of the shaft hole in thehousing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed by meansof the fluid pressure from the high pressure side (H), so that itbecomes a state of being in intimate contact with the side wall surfaceof the annular groove 4100 at the low pressure side (L), as shown inFIG. 25. Here, note that it is needless to say that the outer peripheralring 2000 maintains the state of being in contact (sliding) with theinner peripheral surface of the shaft hole in the housing 5000. Inaddition, with respect to the inner peripheral ring 3100, too, it alsobecomes a state of being in intimate contact with the side wall surfaceof the annular groove 4100 at the low pressure side (L).

<Advantages of the Sealing Device and the Sealing Structure According tothis Practical Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this practical example, thefollowing advantages are achieved in comparison with the sealing deviceand the sealing structure explained in the above-mentioned embodiment.That is, the concave portions 2220 are formed in plurality in aspaced-apart relation in a circumferential direction with respect to oneanother, and hence, the portions (ribs 2211) between adjacent concaveportions 2220 will be in a state of contact with the inner peripheralsurface of the shaft hole in the housing 5000. In addition, because ofthe provision of the plurality of ribs 2211, the reduction in rigidityof the outer peripheral ring 2000 can be suppressed in comparison withthe case where the ribs 2211 are not formed. Accordingly, it is possibleto suppress the outer peripheral ring 2000 from being inclined in theannular groove 4100, thereby making it possible to stabilize themounting state of the outer peripheral ring 2000. Here, note that incases where a construction is adopted in which the plurality of ribs2211 are not formed, there will be a fear that in FIG. 23 and FIG. 25,the outer peripheral ring 2000 may incline in a counter clockwisedirection in these figures.

In addition, in the outer peripheral ring 2000 according to thispractical example, the plurality of ribs 2211 are formed, but these ribs2211 are constructed in such a manner that the length thereof in thecircumferential direction becomes short. For that reason, in thispractical example, too, the concave portions 2220 are formed over alarge area of the outer peripheral surface of the outer peripheral ring2000. Accordingly, in this practical example, too, it is possible toreduce sliding torque to a sufficient extent, similar to the case of theabove-mentioned embodiment.

<Modifications of the First Practical Example>

Sealing devices according to modifications of the first practicalexample of the present disclosure will be explained while referring toFIG. 26 through FIG. 28. In the first practical example, there has beenshown the case where the opposite side surfaces of each rib areconstructed to be vertical from the bottom surfaces of adjacent concaveportions. In contrast to this, in each of the following modifications,there is shown a construction in which a bottom surface of each concaveportion and an outer peripheral surface of each rib in an outerperipheral ring are connected with each other through an inclinedsurface. The other construction in these modifications is the same asthat in the above-mentioned first practical example, so the explanationthereof is omitted.

In these modifications, only the shapes of the concave portions and theribs of the outer peripheral ring are different from those in the firstpractical example. That is, in these modifications, a bottom surface ofeach concave portion and an outer peripheral surface of each rib areconnected with each other through an inclined surface. Hereinafter, thiswill be described in more detail with reference to FIG. 26 through FIG.28. Here, note that FIG. 26 through FIG. 28 show examples in which theshapes of inclined surfaces are respectively different from one another.In addition, in these individual figures, (a) is a part of a perspectiveview of the outer peripheral ring, and (b) is a part of a sideelevational view of the outer peripheral ring. Moreover, in theindividual figures, for the sake of convenience, although an outerperipheral portion, an inner peripheral portion, and a bottom surface ofa concave portion are drawn linearly, they are circular arc in practice.

In a first modification shown in FIG. 26, a bottom surface of a concaveportion 2220 a and an outer peripheral surface of each rib 2211 a in anouter peripheral ring 2000 are connected with each other through aninwardly concaved curved surface (a curved inclined surface) 2211 a 1.

In a second modification shown in FIG. 27, a bottom surface of a concaveportion 2220 b and an outer peripheral surface of each rib 2211 b in anouter peripheral ring 2000 are connected with each other through acurved surface (a curved inclined surface) 2211 b 1 which is bulgedoutwardly at an outer peripheral surface side thereof, and is concavedinwardly at an inner peripheral surface side thereof.

In a third modification shown in FIG. 28, a bottom surface of a concaveportion 2220 c and an outer peripheral surface of each rib 2211 c in anouter peripheral ring 2000 are connected with each other through aplanar inclined surface 2211 c 1.

In the sealing devices (the outer peripheral rings 2000) according tothe various kinds of modifications constructed as described above, too,the same effects as in the above-mentioned first practical example canbe obtained. In addition, in the case of each of the outer peripheralrings 2000 according to the various kinds of modifications, it isconstructed such that a bottom surface of each concave portion and anouter peripheral surface of each rib are connected with each otherthrough an inclined surface. Accordingly, the strength of each rib canbe enhanced as compared with the case of the first practical example,keeping the sliding area thereof with respect to an inner peripheralsurface of a shaft hole in a housing to the same extent as in theabove-mentioned first practical example. As a result, the reduction inrigidity of each of the outer peripheral rings can be suppressed to afurther extent.

Here, note that in the first practical example and the various kinds ofmodifications of the first practical example, in cases where a sealingfunction does not need to be exhibited in a state where fluid pressureis low or in a state where there is no fluid pressure, the outerperipheral rings 2000 can be independently used without the innerperipheral rings 3100, respectively. In this case, a low torque effectcan be enhanced.

Second Practical Example Summary

A sealing device according to a second practical example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereina portion in said outer peripheral ring which slides with respect to theinner peripheral surface of said shaft hole is constructed by a convexportion which is formed so as to extend toward a circumferentialdirection while changing its position to a high pressure side and a lowpressure side in an alternate manner.

According to the sealing device according to this practical example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this practicalexample, the convex portion formed on an outer peripheral surface of theouter peripheral ring is formed so as to extend toward a circumferentialdirection while changing its position to a high pressure side and a lowpressure side in an alternate manner. Accordingly, it is possible tosuppress the outer peripheral ring from being inclined in the annulargroove, thereby making it possible to stabilize the mounting state ofthe outer peripheral ring. Here, note that in this practical example,the convex portion formed so as to extend toward a circumferentialdirection while changing its position to a high pressure side and a lowpressure side in an alternate manner is formed on the outer peripheralsurface of the outer peripheral ring. For that reason, in a state wherethe sealing device is fitted, the concave portion opened to the highpressure side exists in plurality on the outer peripheral surface sideof the outer peripheral ring. Then, fluid is introduced into theseplurality of concave portions from the high pressure side. Accordingly,these plurality of concave portions exhibit the same function as theconcave portion 2220 in the above-mentioned embodiment.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thesecond practical example of the present disclosure will be explainedmore specifically while referring to FIG. 29 through FIG. 37. Here, notethat the basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and firstpractical example, and hence, the same parts are denoted by the samereference numerals and characters, and the explanation thereof isomitted as the case may be.

A sealing device 1000 according to this practical example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this practical example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O ring, but as such there can be adopted otherseal ring such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this second practicalexample of the present disclosure will be explained in further detailwhile referring in particular to FIG. 29 through FIG. 31. An abutmentjoint portion 2100 is formed on the outer peripheral ring 2000 at oneplace in a circumferential direction thereof. In addition, the outerperipheral ring 2000 is formed on its outer peripheral surface with aconvex portion 2212 which protrudes to an outer peripheral surface side,with its surface being in sliding contact with the inner peripheralsurface of the shaft hole in the housing 5000. This convex portion 2212is formed in such a manner that it extends toward a circumferentialdirection while changing its position to a high pressure side (H) and alow pressure side (L) in an alternate manner so as to reach positions onopposite side surfaces in a width direction. More specifically, theconvex portion 2220 is constructed so as to take a wave shape meanderingtoward the circumferential direction. Moreover, this convex portion 2212is formed over the entire periphery of the outer peripheral ring 2000except for the vicinity of the abutment joint portion 2100. Here, notethat in cases where a construction unprovided with the abutment jointportion 2100 is adopted, as will be described later, this convex portion2212 is formed over the entire periphery of the outer peripheral ring2000.

Then, due to the formation of such a convex portion 2212, the outerperipheral ring 2000 is formed at the high pressure side (H) in itsouter peripheral surface with a plurality of third concave portions 2221which are respectively spaced from one another in the circumferentialdirection. Also, the outer peripheral ring 2000 is formed at the lowpressure side (L) in its outer peripheral surface with a plurality offourth concave portions 2222 which are respectively spaced from oneanother in the circumferential direction. The third concave portions2221 are each constructed to extend from an end of the high pressureside (H) to a position which does not reach an end of the low pressureside (L), so that they exhibit a function of introducing fluid thereintofrom the high pressure side (H). Also, the fourth concave portions 2222are each constructed so as to extend from the end of the low pressureside (L) to a position which does not reach the end of the high pressureside (H). Here, the bottom surfaces of the third concave portions 2221and the bottom surfaces of the fourth concave portions 2222 are eachcomposed of a surface which is concentric with the inner peripheralsurface of the outer peripheral ring 2000.

Here, note that the outer peripheral ring 2000 according to thispractical example is constructed such that the abutment joint portion2100, the convex portion 2212, the plurality of third concave portions2221 and the plurality of fourth concave portions 2222 as mentionedabove are formed on an annular member of which the cross section isrectangular. However, this is only an explanation of the shape thereof,but does not necessarily mean that an annular member of a rectangularcross section is used as a material, and processing to form the abutmentjoint portion 2100, the convex portion 2212, the plurality of thirdconcave portions 2221 and the plurality of fourth concave portions 2222is applied to this material. Of course, after an annular member of arectangular cross section has been molded or formed, the abutment jointportion 2100, the convex portion 2212, the plurality of third concaveportions 2221 and the plurality of fourth concave portions 2222 can alsobe obtained by means of cutting work. However, for example, aftermolding or forming a member which has the abutment joint portion 2100 inadvance, the convex portion 2212, the plurality of third concaveportions 2221 and the plurality of fourth concave portions 2222 may beobtained by means of cutting work. In this manner, the method ofproduction thereof is not limited in particular.

A special step cut is employed for the abutment joint portion 2100,similar to the above-mentioned embodiment. However, for the abutmentjoint portion 2100, there can be adopted a straight cut, a bias cut,another step cut, and so on, including but not limited to this. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100. Here, note that in cases where the constructionprovided with the abutment joint portion 2100 is adopted, it isdesirable not to form the third concave portions 2221 and the fourthconcave portions 2222 in the vicinity of the abutment joint portion 2100(refer to FIG. 31). In this case, the outer peripheral surface of theouter peripheral ring 2000 in the vicinity of the abutment joint portion2100 becomes the same surface as an outer peripheral surface of theconvex portion 2212. Accordingly, in this case, those portions of theouter peripheral ring 2000 which slides with respect to the innerperipheral surface of the shaft hole become the outer peripheral surfaceof the convex portion 2212 and an outer peripheral surface of a portionof the outer peripheral ring 2000 in which the third concave portions2221 and the fourth concave portions 2222 are not formed in the vicinityof the abutment joint portion 2100.

The convex portion 2212 according to this the practical example is of anelongated construction, and is constructed such that in the outerperipheral surface of the outer peripheral ring 2000, an area occupiedby the convex portion 2212 is sufficiently narrower as compared with anarea occupied by the plurality of third concave portions 2221 and theplurality of fourth concave portions 2222. In addition, the plurality ofthird concave portions 2221 and the plurality of fourth concave portions2222 are formed over substantially the entire region in thecircumferential direction of the outer peripheral ring 2000. In otherwords, except for the vicinity in which the abutment joint portion 2100is formed and for that portion in which the elongated convex portion2212 is formed, the third concave portions 2221 and the fourth concaveportions 2222 are formed over the entire region of the outer peripheralring 2000 in the circumferential direction. Moreover, it is alsoconstructed such that the opposite side surfaces of the convex portion2212 in this practical example are vertical with respect to the bottomsurfaces of the third concave portions 2221 and the bottom surfaces ofthe fourth concave portions 2222.

In addition, the lower the height of the convex portion 2212 (i.e.,equal to the depth of the third concave portions 2221 and the fourthconcave portions 2222), the higher becomes the rigidity of the portionof the outer peripheral ring 2000 in which the convex portion 2212 isformed. On the other hand, the convex portion 2212 is worn out due tothe relative sliding movement thereof, so the depth of the third concaveportions 2221 and the fourth concave portions 2222 becomes shallower asthe time elapses. For that reason, when the depth of the third concaveportions 2221 becomes too much shallow, it will become impossible tointroduce fluid therein. Accordingly, it is desirable to set an initialheight of the convex portion 2212 by taking into consideration both theabove-mentioned rigidity and the maintenance of introduction of fluideven if the wear progresses with the lapse of time. For example, incases where the thickness of the outer peripheral ring 2000 is 1.7 mm,it is preferable to set the height of the convex portion 2212 to beequal to or more than about 0.1 mm and equal to or less than about 0.3mm.

Moreover, the narrower the width of the convex portion 2212, the morethe torque can be reduced, but if the width is made too much narrow,sealing efficiency and durability will become low. Accordingly, it isdesirable to narrow the width of the convex portion 2212 as much aspossible according to service conditions, etc., to such an extent thatsealing efficiency and durability can be maintained. Here, note that forexample, in cases where the entire length of the width (width in theaxial direction) of the outer peripheral ring 2000 is 1.9 mm, it ispreferable to set the width of the convex portion 2212 to be equal to ormore than about 0.3 mm and equal to or less than about 0.7 mm.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis practical example will be explained, while referring in particularto FIG. 32 through FIG. 35. FIG. 32 through FIG. 34 each show anunloaded state in which an engine is stopped, and there does not exist adifferential pressure (or there exists substantially no differentialpressure) between right-hand side region of the sealing device 1000 andleft-hand side region of the sealing device 1000. Here, note that theouter peripheral ring 2000 in FIG. 32 corresponds to an AA cross sectionin FIG. 30, and the outer peripheral ring 2000 in FIG. 33 corresponds toa BB cross section in FIG. 30, and the outer peripheral ring 2000 inFIG. 34 corresponds to a CC cross section in FIG. 30. FIG. 35 shows astate in which the engine is operated, and fluid pressure in theright-hand side region of the sealing device 1000 has become higher incomparison with that in the left-hand side region of the sealing device1000. Here, note that the outer peripheral ring 2000 in FIG. 35corresponds to the AA cross section in FIG. 30.

In a state where the sealing device 1000 is fitted in an annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the third concave portions 2221 and the fourth concave portions2222 (i.e., the convex portion 2212 and a portion of the outerperipheral ring 2000 in the vicinity of the abutment joint portion 2100in which the third concave portions 2221 and the fourth concave portions2222 are not formed) maintain a state in which they are in contact withthe inner peripheral surface of the shaft hole in the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed by meansof the fluid pressure from the high pressure side (H), so that itbecomes a state of being in intimate contact with the side wall surfaceof the annular groove 4100 at the low pressure side (L), as shown inFIG. 35. Here, note that it is needless to say that the outer peripheralring 2000 maintains the state of being in contact (sliding) with theinner peripheral surface of the shaft hole in the housing 5000. Inaddition, with respect to the inner peripheral ring 3100, too, it alsobecomes a state of being in intimate contact with the side wall surfaceof the annular groove 4100 at the low pressure side (L).

<Advantages of the Sealing Device and the Sealing Structure According tothis Practical Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this practical example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, the convex portion2212 formed on the outer peripheral surface of the outer peripheral ring2000 is formed so as to extend toward the circumferential directionwhile changing its position to the high pressure side (H) and the lowpressure side (L) in an alternate manner. For that reason, the positionin which the outer peripheral surface of the outer peripheral ring 2000slides with respect to the shaft hole in the housing 5000 is not biasedtoward the high pressure side (H) or the low pressure side (L).Accordingly, it is possible to suppress the outer peripheral ring 2000from being inclined in the annular groove 4100, thereby making itpossible to stabilize the mounting state of the outer peripheral ring2000. Here, note that in this practical example, the convex portion 2212is formed in such a manner that it extends toward a circumferentialdirection while changing its position to a high pressure side (H) and alow pressure side (L) in an alternate manner so as to reach positions onopposite side surfaces in the width direction. Accordingly, the positionin which the outer peripheral surface of the outer peripheral ring 2000slides with respect to the shaft hole in the housing 5000 can besuppressed from being biased toward the high pressure side (H) or thelow pressure side (L) in an effective manner.

In addition, the plurality of third concave portions 2221 are formed onthe outer peripheral surface of the outer peripheral ring 2000, so thatfluid can be introduced into these plurality of third concave portions2221 from the high pressure side (H). For that reason, even if the fluidpressure becomes higher, the fluid pressure acts toward the innerperipheral surface side of the outer peripheral ring 2000 in a region inwhich the third concave portions 2221 are formed. Here, in thispractical example, the bottom surfaces of the third concave portions2221 are each composed of a surface which is concentric with the innerperipheral surface of the outer peripheral ring 2000, as a consequenceof which in the region in which the third concave portions 2221 areformed, a direction in which the fluid pressure acts from the innerperipheral surface side and a direction in which the fluid pressure actsfrom the outer peripheral surface side become opposite to each other.Here, note that an arrow in FIG. 35 shows how the fluid pressure actswith respect to the outer peripheral ring 2000. According to this, inthe sealing device 1000 according to this practical example, it ispossible to suppress an increase in pressure toward the outer peripheralsurface side by means of the outer peripheral ring 2000 accompanying anincrease in the fluid pressure, thus making it possible to suppresssliding torque to a low level.

Moreover, as shown in FIG. 35, in the region of the low pressure side(L) from the intimate contact portion of the inner peripheral ring 3100with respect to the outer peripheral ring 2000, it is possible tosuppress the action of the fluid pressure with respect to the innerperipheral surface of the outer peripheral ring 2000. Accordingly, evenif the fluid pressure at the high pressure side (H) increases, it ispossible to suppress an increase in the pressure to the outer peripheralsurface side by the outer peripheral ring 2000.

Further, in this practical example, due to the fact that the thirdconcave portions 2221 and the fourth concave portions 2222 are formedover a wide range of the outer peripheral surface of the outerperipheral ring 2000, it is possible to make the sliding area betweenthe outer peripheral ring 2000 and the inner peripheral surface of theshaft hole in the housing 5000 as narrow as possible. Accordingly, thesliding torque can be reduced very much. Here, note that the slidingarea between the outer peripheral ring 2000 and the inner peripheralsurface of the shaft hole in the housing 5000 is sufficiently narrowerthan the area of intimate contact between the outer peripheral ring 2000and the side wall surface of the annular groove 4100 at the low pressureside (L). With this, it is possible to suppress the outer peripheralring 2000 from sliding with respect to the side wall surface of theannular groove 4100 at the low pressure side (L). Accordingly, the outerperipheral ring 2000 according to this practical example slides at theouter peripheral surface side. For that reason, in comparison with thecase of a seal ring which slides with respect to the side wall surfaceof the annular groove, it becomes easy for a lubricating film (here anoil film) of the fluid being sealed to be formed, so that the slidingtorque can be reduced to a further extent.

In this manner, the generation of heat due to sliding can be suppressedby being able to achieve the reduction of the sliding torque.Accordingly, it becomes possible to use the sealing device 1000according to this practical example in a suitable manner even under ahigh-speed high-pressure environmental condition.

Further, the outer peripheral ring 2000 according to this practicalexample has a symmetrical structure with respect to a central plane inthe width direction (axial direction). Accordingly, it is not necessaryto care about the direction of mounting of the outer peripheral ring2000 at the time when it is mounted or fitted, so this outer peripheralring 2000 is excellent in mountability. In addition, the outerperipheral ring 2000 can be applied under an environment where the highpressure side (H) and the low pressure side (L) are interchanged witheach other. In other words, in FIG. 32 through FIG. 34, the sealingdevice 1000 according to this practical example can also be used in asuitable manner under an environment where fluid pressure at theright-hand side becomes higher in comparison with that at the left-handside, or fluid pressure at the left-hand side becomes higher incomparison with that at the right-hand side.

<Modifications of the Second Practical Example>

Sealing devices according to modifications of the second practicalexample of the present disclosure will be explained while referring toFIG. 36 and FIG. 37. In the modifications explained below, there areshown cases where the shapes of the convex portion, the third concaveportions, and the fourth concave portions formed on the outer peripheralsurface of the outer peripheral ring are different from those of thesecond practical example. The other construction in these modificationsis the same as that in the above-mentioned second practical example, sothe explanation thereof is omitted.

A convex portion 2212 a formed on an outer peripheral surface of anouter peripheral ring 2000 according to a first modification shown inFIG. 36 is formed in such a manner that it extends toward acircumferential direction while changing its position to a high pressureside (H) and a low pressure side (L) in an alternate manner so as toreach positions on opposite side surfaces in a width direction, as inthe case of the above-mentioned second practical example. However, inthe case of the first modification, the convex portion 2212 a isconstructed so as to take a rectangular wave shape extending toward acircumferential direction.

The following feature is the same as that in the case of theabove-mentioned second practical example; that is, due to the formationof such a convex portion 2212 a, there are formed on the outerperipheral surface of the outer peripheral ring 2000 a plurality ofthird concave portions 2221 a which are respectively spaced from oneanother in the circumferential direction, and a plurality of fourthconcave portions 2222 a which are respectively spaced from one anotherin the circumferential direction. In addition, a feature that the thirdconcave portions 2221 a are each constructed to extend from an end ofthe high pressure side (H) to a position which does not reach an end ofthe low pressure side (L) so as to exhibit a function of introducingfluid thereinto from the high pressure side (H) is also the same as inthe case of the above-mentioned second practical example. Moreover, afeature that the fourth concave portions 2222 a are each constructed soas to extend from the end of the low pressure side (L) to a positionwhich does not reach the end of the high pressure side (H) is also thesame as in the case of the above-mentioned second practical example.Further, a feature that the bottom surfaces of the third concaveportions 2221 a and the bottom surfaces of the fourth concave portions2222 a are each composed of a surface which is concentric with the innerperipheral surface of the outer peripheral ring 2000 is also the same asin the case of the above-mentioned second practical example.

It goes without saying that even in this first modification, too, thesame operational effects as in the case of the above-mentioned secondpractical example are obtained.

In addition, a convex portion 2212 b formed on an outer peripheralsurface of an outer peripheral ring 2000 according to a secondmodification shown in FIG. 37 is formed in such a manner that it extendstoward a circumferential direction while changing its position to a highpressure side (H) and a low pressure side (L) in an alternate manner soas to reach positions on opposite side surfaces in a width direction, asin the case of the above-mentioned second practical example. However, inthe case of the second modification, the convex portion 2212 b isconstructed so as to take a triangular wave shape extending toward acircumferential direction.

The following feature is the same as that in the case of theabove-mentioned second practical example; that is, due to the formationof such a convex portion 2212 b, there are formed on the outerperipheral surface of the outer peripheral ring 2000 a plurality ofthird concave portions 2221 b which are respectively spaced from oneanother in the circumferential direction, and a plurality of fourthconcave portions 2222 b which are respectively spaced from one anotherin the circumferential direction. In addition, a feature that the thirdconcave portions 2221 b are each constructed to extend from an end ofthe high pressure side (H) to a position which does not reach an end ofthe low pressure side (L) so as to exhibit a function of introducingfluid thereinto from the high pressure side (H) is also the same as inthe case of the above-mentioned second practical example. Moreover, afeature that the fourth concave portions 2222 b are constructed so as toextend from the end of the low pressure side (L) to a position whichdoes not reach the end of the high pressure side (H) is also the same asin the case of the above-mentioned second practical example. Further, afeature that the bottom surfaces of the third concave portions 2221 band the bottom surfaces of the fourth concave portions 2222 b are eachcomposed of a surface which is concentric with the inner peripheralsurface of the outer peripheral ring 2000 is also the same as in thecase of the above-mentioned second practical example.

It goes without saying that even in this second modification, too, thesame operational effects as in the case of the above-mentioned secondpractical example are obtained.

Here, note that in the second practical example and the various kinds ofmodifications of the second practical example, in cases where a sealingfunction does not need to be exhibited in a state where fluid pressureis low or in a state where there is no fluid pressure, the outerperipheral rings 2000 can be independently used without the innerperipheral rings 3100, respectively. In this case, a low torque effectcan be enhanced.

Third Practical Example Summary

A sealing device according to a third practical example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a plurality of concave portions which are spaced with respect toone another in a circumferential direction and which each extend from anend of a high pressure side to a position which does not arrive at anend of a low pressure side, so as to introduce fluid thereinto from thehigh pressure side; and wherein convex portions each formed betweenadjacent concave portions are formed so as to extend from the lowpressure side toward the high pressure side as they go in the slidingdirection of said outer peripheral ring with respect to said housing.

In addition, a sealing structure according to the third practicalexample of the present disclosure, which is provided with: a shaft and ahousing that rotate relative to each other; and a sealing device that isfitted into an annular groove formed in an outer periphery of said shaftso as to seal an annular gap between said shaft and said housing,thereby to hold a fluid pressure in a region to be sealed which isconstructed such that the fluid pressure therein changes; the sealingdevice comprises: an outer peripheral ring made of resin that is inintimate contact with a side wall surface of said annular groove at alow pressure side thereof, and slides with respect to an innerperipheral surface of a shaft hole in said housing through which saidshaft is inserted; and an inner peripheral ring made of a rubber-likeelastic body that is in intimate contact with an inner peripheralsurface of said outer peripheral ring and a groove bottom surface ofsaid annular groove, respectively, thereby to push said outer peripheralring toward an outer peripheral surface side thereof; wherein said outerperipheral ring is formed on its outer peripheral surface with aplurality of concave portions which are spaced with respect to oneanother in a circumferential direction and which each extend from an endof a high pressure side to a position which does not arrive at an end ofa low pressure side, so as to introduce fluid thereinto from the highpressure side; and wherein convex portions each formed between adjacentconcave portions are formed so as to extend from the low pressure sidetoward the high pressure side as they go in the sliding direction ofsaid outer peripheral ring with respect to said housing.

According to the sealing device according to this practical example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this practicalexample, the convex portions each formed between adjacent concaveportions are formed so as to extend from the low pressure side towardthe high pressure side as they go in the sliding direction of the outerperipheral ring with respect to the housing. For that reason, the fluidintroduced into the concave portions in accordance with the relativerotation between the housing and the outer peripheral ring activelyflows from the high pressure side to the low pressure side as well astoward the sliding direction of the housing with respect to the outerperipheral ring. As a result of this, the flow of fluid concentrates onthe vicinity of wedge-shaped tip ends formed by low pressure sideportions on the outer peripheral surface of the outer peripheral ring inwhich the concave portions are not formed and the convex portions. Then,dynamic pressure is generated due to this concentration of the flow offluid, so the outer peripheral ring is pushed toward the innerperipheral surface side. Accordingly, due to this dynamic pressure, too,an increase in pressure toward the outer peripheral surface by means ofthe outer peripheral ring can be suppressed, thus making it possible tosuppress sliding torque to a low level.

Further, because of the provision of the plurality of convex portions,the reduction in rigidity of the outer peripheral ring can besuppressed. In addition, these plurality of convex portions are in astate of contact with the inner peripheral surface of the shaft hole inthe housing, so that the outer peripheral ring can be suppressed frombeing inclined in the annular groove, thereby making it possible tostabilize the mounting state of the outer peripheral ring.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thethird practical example of the present disclosure will be explained morespecifically while referring to FIG. 38 through FIG. 43. Here, note thatthe basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts are denoted bythe same reference numerals and characters, and the explanation thereofis omitted as the case may be.

A sealing device 1000 according to this practical example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this practical example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O ring, but as such there can be adopted otherseal ring such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this third practical exampleof the present disclosure will be explained in further detail whilereferring in particular to FIG. 38 through FIG. 40 and FIG. 42. Anabutment joint portion 2100 is formed on the outer peripheral ring 2000at one place in a circumferential direction thereof. In addition, theouter peripheral ring 2000 is formed on its outer peripheral surfacewith a plurality of concave portions 2220 which are respectively spacedfrom one another in the circumferential direction.

Here, note that the outer peripheral ring 2000 according to thispractical example is constructed such that the abutment joint portion2100 and the plurality of concave portions 2220 as mentioned above areformed on an annular member of which the cross section is rectangular.However, this is only an explanation of the shape thereof, but does notnecessarily mean that an annular member of a rectangular cross sectionis used as a material, and processing to form the abutment joint portion2100 and the plurality of concave portions 2220 is applied to thismaterial. Of course, after an annular member of a rectangular crosssection has been molded or formed, the abutment joint portion 2100 andthe plurality of concave portions 2220 can also be obtained by means ofcutting work. However, for example, after molding or forming a memberwhich has the abutment joint portion 2100 in advance, the plurality ofconcave portions 2220 may be obtained by means of cutting work. In thismanner, the method of production thereof is not limited in particular.

A special step cut is employed for the abutment joint portion 2100,similar to the above-mentioned embodiment. However, for the abutmentjoint portion 2100, there can be adopted a straight cut, a bias cut,another step cut, and so on, including but not limited to this. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100.

In this practical example, the concave portions 2220 are formed inplurality in a spaced-apart relation with respect to one another in thecircumferential direction. Here, note that in this practical example,the plurality of concave portions 2220 are arranged so as to be at equalintervals, except for the vicinity of the abutment joint portion 2100.

In addition, convex portions 2213 are each formed between adjacentconcave portions 2220, respectively, by the formation of the pluralityof concave portions 2220. The convex portions 2213 are formed so as toextend from a low pressure side (L) toward a high pressure side (H) asthey go in the sliding direction of the outer peripheral ring 2000 withrespect to the housing 5000.

Moreover, the concave portions 2220 are each constructed to extend froman end of the high pressure side (H) to a position which does not reachan end of the low pressure side (L). More specifically, the concaveportions 2220 are formed so as to extend to the vicinity of the otherend of the outer peripheral ring 2000 at the low pressure side (L).Here, note that in this practical example, too, the bottom surfaces ofthe concave portions 2220 are composed of surfaces which are concentricwith the inner peripheral surface of the outer peripheral ring 2000.

Here, note that in the outer peripheral surface side of the outerperipheral ring 2000, an outer peripheral surface of a portion in whichthe concave portions 2220 are not formed in the vicinity of the abutmentjoint portion 2100, and outer peripheral surfaces of the convex portions2213 and low pressure side convex portions 2210 are composed of the samesurface. That is, these peripheral surfaces are concentric with theinner peripheral surface of the outer peripheral ring 2000. Then, acontinuous annular surface is formed by the outer peripheral surface ofthat portion in which the concave portions 2220 are not formed in thevicinity of the abutment joint portion 2100 and the outer peripheralsurfaces of the low pressure side convex portions 2210. This continuousannular surface functions as a sealing surface at the outer peripheralsurface side in the outer peripheral ring 2000.

The shallower the depth of the concave portions 2220, the higher becomesthe rigidity of those portions of the outer peripheral ring 2000 inwhich the convex portions 2213 and the low pressure side convex portions2210 are formed. On the other hand, these convex portions 2213 and thelow pressure side convex portions 2210 are worn out due to the relativesliding movement thereof, so the depth of the concave portions 2220becomes shallower as the time elapses. For that reason, when the depthof the concave portions 2220 becomes too much shallow, it will becomeimpossible to introduce fluid therein. Accordingly, it is desirable toset an initial depth of the concave portions 2220 by taking intoconsideration both the above-mentioned rigidity and the maintenance ofintroduction of fluid even if the wear progresses with the lapse oftime. For example, in cases where the thickness of the outer peripheralring 2000 is 1.7 mm, it is preferable to set the depth of the concaveportions 2220 to be equal to or more than about 0.1 mm and equal to orless than about 0.3 mm.

In addition, with respect to the width (width in the axial direction) ofthe concave portions 2220, the wider the width of the concave portions2220, the narrower becomes the width of the low pressure side convexportions 2210. The narrower this width becomes, the more the torque canbe reduced, but if the width is made too much narrow, sealing efficiencyand durability will become low. Accordingly, it is desirable to narrowthe width concerned as much as possible according to service conditions,etc., to such an extent that sealing efficiency and durability can bemaintained. Here, note that for example, in cases where the entirelength of the width (width in the axial direction) of the outerperipheral ring 2000 is 1.9 mm, it is preferable to set the width ofeach of the low pressure side convex portions 2210 to be equal to ormore than about 0.3 mm and equal to or less than about 0.7 mm. Also, itis preferable to set the width in the circumferential direction of theconvex portions 2213 to be equal to or more than 0.3 mm and equal to orless than 0.7 mm.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis practical example will be explained, while referring in particularto FIG. 41 through FIG. 43. FIG. 41 shows an unloaded state in which anengine is stopped, and there does not exist a differential pressure (orthere exists substantially no differential pressure) between right-handside region of the sealing device 1000 and left-hand side region of thesealing device 1000. Here, note that FIG. 41 is a schematic crosssectional view (i.e., a cross sectional view including an axis of ashaft 4000) of a portion in which a concave portion 2220 is formed inthe outer peripheral ring 2000, wherein the sealing device 1000 in FIG.41 corresponds to one in an AA cross section in FIG. 38. FIG. 42 is apartially broken perspective view in the outer peripheral ring 2000,showing the relation between the sliding direction of the outerperipheral ring 2000 with respect to the housing 5000 and the flow offluid. FIG. 43 shows a state in which the engine is operated, and fluidpressure in the right-hand side region of the sealing device 1000 hasbecome higher in comparison with that in the left-hand side region ofthe sealing device 1000. Here, note that FIG. 43 is a schematic crosssectional view (i.e., a cross sectional view including an axis of ashaft 4000) of a portion in which a concave portion 2220 is formed inthe outer peripheral ring 2000, wherein the sealing device 1000 in FIG.43 corresponds to one in an AA cross section in FIG. 38.

In a state where the sealing device 1000 is fitted in an annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portions 2220 (i.e., the low pressure side convexportions 2210, the convex portions 2213 and that portion of the outerperipheral ring 2000 in the vicinity of the abutment joint portion 2100in which a concave portion 2220 is not formed) maintain a state in whichthey are in contact with the inner peripheral surface of the shaft holein the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed by meansof the fluid pressure from the high pressure side (H), so that itbecomes a state of being in intimate contact with the side wall surfaceof the annular groove 4100 at the low pressure side (L), as shown inFIG. 43. Here, note that it is needless to say that the outer peripheralring 2000 maintains the state of being in contact (sliding) with theinner peripheral surface of the shaft hole in the housing 5000. Inaddition, with respect to the inner peripheral ring 3100, too, it alsobecomes a state of being in intimate contact with the side wall surfaceof the annular groove 4100 at the low pressure side (L).

Moreover, the plurality of convex portions 2213 formed on the outerperipheral surface of the outer peripheral ring 2000 according to thispractical example are formed so as to extend from the low pressure side(L) toward the high pressure side (H) as they go in the slidingdirection (in the direction of an arrow R in FIG. 42) of the outerperipheral ring 2000 with respect to the housing 5000. For that reason,in accordance with relative rotation between the housing 5000 and theouter peripheral ring 2000, the fluid introduced in the concave portions2220 actively flows from the high pressure side (H) to the low pressureside (L) as well as toward the sliding direction of the housing 5000with respect to the outer peripheral ring 2000 (i.e., flows in thedirection of an arrow X in FIG. 42).

<Advantages of the Sealing Device and the Sealing Structure According tothis Practical Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this practical example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, by means of theconvex portions 2213 formed on the outer peripheral ring 2000, the fluidintroduced in the concave portions 2220 actively flows toward thedirection of the arrow X in FIG. 42 in accordance with relative rotationbetween the housing 5000 and the outer peripheral ring 2000. As a resultof this, the flow of fluid concentrates on the vicinity of wedge-shapedtip ends formed by the low pressure side convex portions 2210 and theconvex portions 2213, among the concave portions 2220. Then, dynamicpressure is generated due to this concentration of the flow of fluid, sothe outer peripheral ring 2000 is pushed toward the inner peripheralsurface side. Accordingly, due to this dynamic pressure, too, anincrease in pressure toward the outer peripheral surface by means of theouter peripheral ring 2000 can be suppressed, thus making it possible tosuppress sliding torque to a low level.

Further, in this practical example, because of the provision of theplurality of convex portions 2213, the reduction in rigidity of theouter peripheral ring 2000 can be suppressed in comparison with the casewhere the convex portions 2213 are not formed. In addition, theseplurality of convex portions 2213 are in a state of contact with theinner peripheral surface of the shaft hole in the housing 5000, so thatthe outer peripheral ring 2000 can be suppressed from being inclined inthe annular groove 4100, thereby making it possible to stabilize themounting state of the outer peripheral ring 2000. Here, because theconvex portions 2213 are formed in such a manner that they each extendfrom the end of the high pressure side (H) to the end of the lowpressure side (L) in the outer peripheral ring 2000, it is possible tosuppress the tilt or inclination of the outer peripheral ring 2000 in aneffective manner. Here, note that in cases where a construction isadopted in which the plurality of convex portions 2213 are not formed,there will be a fear that in FIG. 41 and FIG. 43, the outer peripheralring 2000 may incline in a counter clockwise direction in these figures.

In addition, in this practical example, too, the concave portions 2220are formed over a large area of the outer peripheral surface of theouter peripheral ring 2000. Accordingly, in this practical example, too,it is possible to reduce sliding torque to a sufficient extent, similarto the case of the above-mentioned embodiment.

Here, note that in the third practical example, in cases where a sealingfunction does not need to be exhibited in a state where fluid pressureis low or in a state where there is no fluid pressure, the outerperipheral ring 2000 can be independently used without the innerperipheral ring 3100. In this case, a low torque effect can be enhanced.

Fourth Practical Example Summary

A sealing device according to a fourth practical example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a plurality of concave portions which are spaced with respect toone another in a circumferential direction and which each extend from anend of a high pressure side to a position which does not arrive at anend of a low pressure side, so as to introduce fluid thereinto from thehigh pressure side; and wherein convex portions each formed betweenadjacent concave portions are formed so as to extend from the highpressure side toward the low pressure side as they go in the slidingdirection of said outer peripheral ring with respect to said housing.

In addition, a sealing structure according to the fourth practicalexample of the present disclosure, which is provided with: a shaft and ahousing that rotate relative to each other; and a sealing device that isfitted into an annular groove formed in an outer periphery of said shaftso as to seal an annular gap between said shaft and said housing,thereby to hold a fluid pressure in a region to be sealed which isconstructed such that the fluid pressure therein changes; the sealingdevice comprises: an outer peripheral ring made of resin that is inintimate contact with a side wall surface of said annular groove at alow pressure side thereof, and slides with respect to an innerperipheral surface of a shaft hole in said housing through which saidshaft is inserted; and an inner peripheral ring made of a rubber-likeelastic body that is in intimate contact with an inner peripheralsurface of said outer peripheral ring and a groove bottom surface ofsaid annular groove, respectively, thereby to push said outer peripheralring toward an outer peripheral surface side thereof; wherein said outerperipheral ring is formed on its outer peripheral surface with aplurality of concave portions which are spaced with respect to oneanother in a circumferential direction and which each extend from an endof a high pressure side to a position which does not arrive at an end ofa low pressure side, so as to introduce fluid thereinto from the highpressure side; and wherein convex portions each formed between adjacentconcave portions are formed so as to extend from the high pressure sidetoward the low pressure side as they go in the sliding direction of saidouter peripheral ring with respect to said housing.

According to the sealing device according to this practical example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this practicalexample, the convex portions each formed between adjacent concaveportions are formed so as to extend from the high pressure side towardthe low pressure side as they go in the sliding direction of the outerperipheral ring with respect to the housing. For that reason, the fluidintroduced into the concave portions in accordance with the relativerotation between the housing and the outer peripheral ring activelyflows from the low pressure side to the high pressure side as well astoward the sliding direction of the housing with respect to the outerperipheral ring. Thus, the fluid introduced in the concave portions actsin such a manner as to be caused to return to the high pressure side inaccordance with relative rotation between the housing and the outerperipheral ring, so it is possible to suppress the leakage of fluid.

Further, because of the provision of the plurality of convex portions,the reduction in rigidity of the outer peripheral ring can besuppressed. In addition, these plurality of convex portions are in astate of contact with the inner peripheral surface of the shaft hole inthe housing, so that the outer peripheral ring can be suppressed frombeing inclined in the annular groove, thereby making it possible tostabilize the mounting state of the outer peripheral ring.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thefourth practical example of the present disclosure will be explainedmore specifically while referring to FIG. 44 through FIG. 49. Here, notethat the basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts are denoted bythe same reference numerals and characters, and the explanation thereofis omitted as the case may be.

A sealing device 1000 according to this practical example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this practical example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O ring, but as such there can be adopted otherseal ring such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this fourth practicalexample of the present disclosure will be explained in further detailwhile referring in particular to FIG. 44 through FIG. 46 and FIG. 48. Anabutment joint portion 2100 is formed on the outer peripheral ring 2000at one place in a circumferential direction thereof. In addition, theouter peripheral ring 2000 is formed on its outer peripheral surfacewith a plurality of concave portions 2220 which are respectively spacedfrom one another in a circumferential direction.

Here, note that the outer peripheral ring 2000 according to thispractical example is constructed such that the abutment joint portion2100 and the plurality of concave portions 2220 as mentioned above areformed on an annular member of which the cross section is rectangular.However, this is only an explanation of the shape thereof, but does notnecessarily mean that an annular member of a rectangular cross sectionis used as a material, and processing to form the abutment joint portion2100 and the plurality of concave portions 2220 is applied to thismaterial. Of course, after an annular member of a rectangular crosssection has been molded or formed, the abutment joint portion 2100 andthe plurality of concave portions 2220 can also be obtained by means ofcutting work. However, for example, after molding or forming a memberwhich has the abutment joint portion 2100 in advance, the plurality ofconcave portions 2220 may be obtained by means of cutting work. In thismanner, the method of production thereof is not limited in particular.

A special step cut is employed for the abutment joint portion 2100,similar to the above-mentioned embodiment. However, for the abutmentjoint portion 2100, there can be adopted a straight cut, a bias cut,another step cut, and so on, including but not limited to this. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100.

In this practical example, the concave portions 2220 are formed inplurality in a spaced-apart relation with respect to one another in thecircumferential direction. Here, note that in this practical example,the plurality of concave portions 2220 are arranged so as to be at equalintervals, except for the vicinity of the abutment joint portion 2100.

In addition, convex portions 2214 are each formed between adjacentconcave portions 2220, respectively, by the formation of the pluralityof concave portions 2220. The convex portions 2214 are formed so as toextend from a high pressure side (H) toward a low pressure side (L) asthey go in the sliding direction of the outer peripheral ring 2000 withrespect to the housing 5000.

Moreover, the concave portions 2220 are each constructed to extend froman end of the high pressure side (H) to a position which does not reachan end of the low pressure side (L). More specifically, the concaveportions 2220 are each formed so as to extend to the vicinity of theother end of the outer peripheral ring 2000 at the low pressure side(L). Here, note that in this practical example, too, the bottom surfacesof the concave portions 2220 are composed of surfaces which areconcentric with the inner peripheral surface of the outer peripheralring 2000.

Here, note that in the outer peripheral surface side of the outerperipheral ring 2000, an outer peripheral surface of a portion in whichthe concave portions 2220 are not formed in the vicinity of the abutmentjoint portion 2100, and outer peripheral surfaces of the convex portions2214 and low pressure side convex portions 2210 are composed of the samesurface. That is, these peripheral surfaces are concentric with theinner peripheral surface of the outer peripheral ring 2000. Then, acontinuous annular surface is formed by the outer peripheral surface ofthat portion in which the concave portions 2220 are not formed in thevicinity of the abutment joint portion 2100 and the outer peripheralsurfaces of the low pressure side convex portions 2210. This continuousannular surface functions as a sealing surface at the outer peripheralsurface side in the outer peripheral ring 2000.

The shallower the depth of the concave portions 2220, the higher becomesthe rigidity of those portions of the outer peripheral ring 2000 inwhich the convex portions 2214 and the low pressure side convex portions2210 are formed. On the other hand, these convex portions 2214 and thelow pressure side convex portions 2210 are worn out due to the relativesliding movement thereof, so the depth of the concave portions 2220becomes shallower as the time elapses. For that reason, when the depthof the concave portions 2220 becomes too much shallow, it will becomeimpossible to introduce fluid therein. Accordingly, it is desirable toset an initial depth of the concave portions 2220 by taking intoconsideration both the above-mentioned rigidity and the maintenance ofintroduction of fluid even if the wear progresses with the lapse oftime. For example, in cases where the thickness of the outer peripheralring 2000 is 1.7 mm, it is preferable to set the depth of the concaveportions 2220 to be equal to or more than about 0.1 mm and equal to orless than about 0.3 mm.

In addition, with respect to the width (width in the axial direction) ofthe concave portions 2220, the wider the width of the concave portions2220, the narrower becomes the width of the low pressure side convexportions 2210. The narrower this width becomes, the more the torque canbe reduced, but if the width is made too much narrow, sealing efficiencyand durability will become low. Accordingly, it is desirable to narrowthe width concerned as much as possible according to service conditions,etc., to such an extent that sealing efficiency and durability can bemaintained. Here, note that for example, in cases where the entirelength of the width (width in the axial direction) of the outerperipheral ring 2000 is 1.9 mm, it is preferable to set the width ofeach of the convex portions 2210 to be equal to or more than about 0.3mm and equal to or less than about 0.7 mm. Also, it is preferable to setthe width in the circumferential direction of the convex portions 2214to be equal to or more than 0.3 mm and equal to or less than 0.7 mm.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis practical example will be explained, while referring in particularto FIG. 47 through FIG. 49. FIG. 47 shows an unloaded state in which anengine is stopped, and there does not exist a differential pressure (orthere exists substantially no differential pressure) between right-handside region of the sealing device 1000 and left-hand side region of thesealing device 1000. Here, note that FIG. 47 is a schematic crosssectional view (i.e., a cross sectional view including an axis of ashaft 4000) of a portion in which a concave portion 2220 is formed inthe outer peripheral ring 2000, wherein the sealing device 1000 in FIG.47 corresponds to one in an AA cross section in FIG. 44. FIG. 48 is apartially broken perspective view in the outer peripheral ring 2000,showing the relation between the sliding direction of the outerperipheral ring 2000 with respect to the housing 5000 and the flow offluid. FIG. 49 shows a state in which the engine is operated, and fluidpressure in the right-hand side region of the sealing device 1000 hasbecome higher in comparison with that in the left-hand side region ofthe sealing device 1000. Here, note that FIG. 49 is a schematic crosssectional view (i.e., a cross sectional view including an axis of ashaft 4000) of a portion in which a concave portion 2220 is formed inthe outer peripheral ring 2000, wherein the sealing device 1000 in FIG.49 corresponds to one in an AA cross section in FIG. 44.

In a state where the sealing device 1000 is fitted in an annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portions 2220 (i.e., the low pressure side convexportions 2210, the convex portions 2214 and that portion of the outerperipheral ring 2000 in the vicinity of the abutment joint portion 2100in which a concave portion 2220 is not formed) maintain a state in whichthey are in contact with the inner peripheral surface of the shaft holein the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed by meansof the fluid pressure from the high pressure side (H), so that itbecomes a state of being in intimate contact with the side wall surfaceof the annular groove 4100 at the low pressure side (L), as shown inFIG. 49. Here, note that it is needless to say that the outer peripheralring 2000 maintains the state of being in contact (sliding) with theinner peripheral surface of the shaft hole in the housing 5000. Inaddition, with respect to the inner peripheral ring 3100, too, it alsobecomes a state of being in intimate contact with the side wall surfaceof the annular groove 4100 at the low pressure side (L).

Moreover, the plurality of convex portions 2214 formed on the outerperipheral surface of the outer peripheral ring 2000 according to thispractical example are formed so as to extend from the high pressure side(H) toward the low pressure side (L) as they go in the sliding direction(in the direction of an arrow R in FIG. 48) of the outer peripheral ring2000 with respect to the housing 5000. For that reason, in accordancewith relative rotation between the housing 5000 and the outer peripheralring 2000, the fluid introduced in the concave portions 2220 activelyflows from the low pressure side (L) to the high pressure side (H) aswell as toward the sliding direction of the housing 5000 with respect tothe outer peripheral ring 2000 (i.e., flows in the direction of an arrowX in FIG. 48).

<Advantages of the Sealing Device and the Sealing Structure According tothis Practical Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this practical example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, by means of theconvex portions 2214 formed on the outer peripheral ring 2000, the fluidintroduced in the concave portions 2220 actively flows toward thedirection of the arrow X in FIG. 48 in accordance with relative rotationbetween the housing 5000 and the outer peripheral ring 2000. Thus, thefluid introduced in the concave portions 2220 acts in such a manner asto be caused to return to the high pressure side (H) in accordance withrelative rotation between the housing 5000 and the outer peripheral ring2000. Accordingly, the leakage of the fluid can be suppressed.

Further, in this practical example, because of the provision of theplurality of convex portions 2214, the reduction in rigidity of theouter peripheral ring 2000 can be suppressed in comparison with the casewhere the convex portions 2214 are not formed. In addition, theseplurality of convex portions 2214 are in a state of contact with theinner peripheral surface of the shaft hole in the housing 5000, so thatthe outer peripheral ring 2000 can be suppressed from being inclined inthe annular groove 4100, thereby making it possible to stabilize themounting state of the outer peripheral ring 2000. Here, because theconvex portions 2214 are formed in such a manner that they each extendfrom the end of the high pressure side (H) to the end of the lowpressure side (L) in the outer peripheral ring 2000, it is possible tosuppress the tilt or inclination of the outer peripheral ring 2000 in aneffective manner. Here, note that in cases where a construction isadopted in which the plurality of convex portions 2214 are not formed,there will be a fear that in FIG. 47 and FIG. 49, the outer peripheralring 2000 may incline in a counter clockwise direction in these figures.

In addition, in this practical example, too, the concave portions 2220are formed over a large area of the outer peripheral surface of theouter peripheral ring 2000. Accordingly, in this practical example, too,it is possible to reduce sliding torque to a sufficient extent, similarto the case of the above-mentioned embodiment.

Here, note that in the practical example, in cases where a sealingfunction does not need to be exhibited in a state where fluid pressureis low or in a state where there is no fluid pressure, the outerperipheral ring 2000 can be independently used without the innerperipheral ring 3100. In this case, a low torque effect can be enhanced.

Fourth Reference Example Summary

A sealing device according to a fourth reference example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side; and whereinsaid outer peripheral ring is formed on its inner peripheral surfaceside and at the low pressure side with an inner peripheral convexportion which is constructed so as to extend toward the inner peripheralsurface side, and which, at the time of holding the fluid pressure, ispushed by said inner peripheral ring into intimate contact with the sidewall surface at the low pressure side in said annular groove.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, the inner peripheral convex portion formed on the outerperipheral ring is pushed by the inner peripheral ring into intimatecontact with the side wall surface at the low pressure side in theannular groove. Accordingly, the outer peripheral ring is held in astate of intimate contact with the side wall surface at the low pressureside in the annular groove in a stable manner, so that the posture ofthe outer peripheral ring can be stabilized.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thefourth reference example of the present disclosure will be explainedmore specifically while referring to FIG. 50 through FIG. 54. Here, notethat the basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts are denoted bythe same reference numerals and characters, and the explanation thereofis omitted as the case may be.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this reference example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O ring, but as such there can be adopted otherseal ring such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this fourth referenceexample of the present disclosure will be explained in further detailwhile referring in particular to FIG. 50 through FIG. 52. An abutmentjoint portion 2100 is formed on the outer peripheral ring 2000 at oneplace in a circumferential direction thereof. In addition, the outerperipheral ring 2000 is formed on its outer peripheral surface with aconcave portion 2220 for introducing fluid. Further, the outerperipheral ring 2000 is formed on its inner peripheral surface and atthe low pressure side with the inner peripheral convex portion 2312which is constructed so as to extend toward the inner peripheral surfaceside.

Here, note that the outer peripheral ring 2000 according to thisreference example is constructed such that the abutment joint portion2100, the concave portion 2220 and the inner peripheral convex portion2312 as mentioned above are formed on an annular member of which thecross section is rectangular. However, this is only an explanation ofthe shape thereof, but does not necessarily mean that an annular memberof a rectangular cross section is used as a material, and processing toform the abutment joint portion 2100, the concave portion 2220 and theinner peripheral convex portion 2312 is applied to this material. Ofcourse, after an annular member of a rectangular cross section has beenmolded or formed, the abutment joint portion 2100, the concave portion2220 and the inner peripheral convex portion 2312 can also be obtainedby means of cutting work. However, for example, after molding or forminga member which has the abutment joint portion 2100 in advance, theconcave portion 2220 and the inner peripheral convex portion 2312 may beobtained by means of cutting work. In this manner, the method ofproduction thereof is not limited in particular.

A special step cut is employed for the abutment joint portion 2100,similar to the above-mentioned embodiment. However, for the abutmentjoint portion 2100, there can be adopted a straight cut, a bias cut,another step cut, and so on, including but not limited to this. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100.

In this reference example, too, the concave portion 2220 is formed overthe entire periphery of the outer peripheral ring 2000 except for thevicinity of the abutment joint portion 2100. The concave portion 2220 isthe same as explained in the above-mentioned embodiment, and so, thedetailed explanation thereof is omitted.

In addition, in this reference example, the inner peripheral convexportion 2312 is formed over the entire periphery of the outer peripheralring 2000 except for the vicinity of the abutment joint portion 2100.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis reference example will be explained, while referring in particularto FIG. 53 and FIG. 54. FIG. 53 shows an unloaded state in which anengine is stopped, and there does not exist a differential pressure (orthere exists substantially no differential pressure) between right-handside region of the sealing device 1000 and left-hand side region of thesealing device 1000. FIG. 54 shows a state in which the engine isoperated, and fluid pressure in the right-hand side of the sealingdevice 1000 region has become higher in comparison with that in theleft-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in an annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portion 2220 (i.e., the low pressure side convexportion 2210 and a portion of the outer peripheral ring 2000 in thevicinity of the abutment joint portion 2100 in which the concave portion2220 is not formed) maintain a state in which they are in contact withthe inner peripheral surface of the shaft hole in the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed to thelow pressure side (L) by means of the fluid pressure from the highpressure side (H), so that it becomes a state of being in intimatecontact with the side wall surface of the annular groove 4100 at the lowpressure side (L), as shown in FIG. 54. Here, note that it is needlessto say that the outer peripheral ring 2000 maintains the state of beingin contact (sliding) with the inner peripheral surface of the shaft holein the housing 5000.

In addition, the inner peripheral convex portion 2312 in the outerperipheral ring 2000 is pushed by the inner peripheral ring 3100, sothat it is maintained in a state of being in intimate contact with theside wall surface of the annular groove 4100 at the low pressure side(L).

<Advantages of the Sealing Device and the Sealing Structure According tothis Reference Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, the innerperipheral convex portion 2312 in the outer peripheral ring 2000 ispushed by the inner peripheral ring 3100, so that it is maintained inthe state of intimate contact with the side wall surface of the annulargroove 4100 at the low pressure side (L). Accordingly, it is possible tosuppress the outer peripheral ring 2000 from being inclined in theannular groove 4100, thereby making it possible to stabilize the postureof the outer peripheral ring 2000.

Fifth Reference Example Summary

A sealing device according to a fifth reference example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; an inner peripheral ring made of arubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; and aposition limiting ring that is fitted in said annular groove at a highpressure side and at an inner peripheral surface side inner than saidouter peripheral ring, and limits movement of said inner peripheral ringtoward the high pressure side; wherein said outer peripheral ring isformed on its outer peripheral surface with a concave portion whichextends from an end of a high pressure side to a position which does notarrive at an end of a low pressure side, so as to introduce fluidthereinto from the high pressure side.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, the movement of the inner peripheral ring toward the highpressure side is limited by means of the position limiting ring. As aresult of this, it is possible to suppress the pushing position of theinner peripheral ring with respect to the outer peripheral ring frombeing biased toward the high pressure side, i.e., toward a side in theouter peripheral surface at which the concave portion is formed.Accordingly, it is possible to stabilize the posture of the outerperipheral ring.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thefifth reference example of the present disclosure will be explained morespecifically while referring to FIG. 55 through FIG. 59. Here, note thatthe basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts are denoted bythe same reference numerals and characters, and the explanation thereofis omitted as the case may be.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 made of resin, an inner peripheral ring3100 made of a rubber-like elastic body, and a position limiting ring3500. The inner peripheral ring 3100 according to this reference exampleis a so-called O ring having a circular cross sectional shape. However,the inner peripheral ring 3100 is not limited to the O ring, but as suchthere can be adopted other seal ring such as a rectangular or polygonalring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

The construction of the outer peripheral ring 2000 is the same asexplained in the above-mentioned embodiment, and so, the detailedexplanation thereof is omitted.

Then, in the sealing device 1000 according to this reference example,provision is made for the position limiting ring 3500 which is fitted inan annular groove 4100 at a high pressure side (H) and at an innerperipheral surface side inner than the outer peripheral ring 2000, andlimits movement of the inner peripheral ring 3100 toward the highpressure side (H). For the material of this position limiting ring 3500,it is not limited in particular, but a rubber material, a resinmaterial, etc., can be adopted as the case may be. In addition, in orderto improve the mountability (easiness in fitting) of the positionlimiting ring 3500 with respect to the annular groove 4100, the positionlimiting ring 3500 may also be formed with an abutment joint portion, asin the case of the outer peripheral ring 2000. Here, note that to thisabutment joint portion, there can be applied a variety of kinds ofwell-known techniques such as a straight cut, a bias cut, a special stepcut, and so on.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis reference example will be explained, while referring in particularto FIG. 55 and FIG. 56. FIG. 55 shows an unloaded state in which anengine is stopped, and there does not exist a differential pressure (orthere exists substantially no differential pressure) between right-handside region of the sealing device 1000 and left-hand side region of thesealing device 1000. FIG. 56 shows a state in which the engine isoperated, and fluid pressure in the right-hand side region of thesealing device 1000 has become higher in comparison with that in theleft-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in the annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portion 2220 (i.e., the low pressure side convexportion 2210 and a portion of the outer peripheral ring 2000 in thevicinity of the abutment joint portion 2100 in which the concave portion2220 is not formed) maintain a state in which they are in contact withthe inner peripheral surface of the shaft hole in the housing 5000.

In addition, in this reference example, the position limiting ring 3500is fitted in the annular groove 4100, so the range of movement of theinner peripheral ring 3100 is limited. In other words, the movement ofthe inner peripheral ring 3100 to the right side in FIG. 55 (the highpressure side (H) at the time of occurrence of differential pressure) islimited or restricted.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed to thelow pressure side (L) by means of the fluid pressure from the highpressure side (H), so that it becomes a state of being in intimatecontact with the side wall surface of the annular groove 4100 at the lowpressure side (L), as shown in FIG. 56. Here, note that it is needlessto say that the outer peripheral ring 2000 maintains the state of beingin contact (sliding) with the inner peripheral surface of the shaft holein the housing 5000. In addition, with respect to the inner peripheralring 3000, too, it also becomes a state of being in intimate contactwith the side wall surface of the annular groove 4100 at the lowpressure side (L).

<Advantages of the Sealing Device and the Sealing Structure According tothis Reference Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, the movement ofthe inner peripheral ring 3100 toward the high pressure side (H) islimited by means of the position limiting ring 3500. As a result ofthis, it is possible to suppress the pushing position of the innerperipheral ring 3100 with respect to the outer peripheral ring 2000 frombeing biased toward the high pressure side (H), i.e., toward a side inthe outer peripheral surface at which the concave portion 2220 isformed. Accordingly, it is possible to stabilize the posture of theouter peripheral ring 2000. Here, note that in the case of thisreference example, as shown in FIG. 55, even in a state wheredifferential pressure is not generated, it is possible to suppress thepushing position of the inner peripheral ring 3100 with respect to theouter peripheral ring 2000 from being biased toward the right side inthis figure. Accordingly, in the state where differential pressure isnot generated, too, it is possible to stabilize the posture of the outerperipheral ring 2000.

Here, at the time when differential pressure has been generated, inorder to make the inner peripheral ring 3100 into intimate contact withthe side wall surface at the low pressure side (L) in the annular groove4100 in a more reliable manner, it is desirable to cause the fluidpressure to act on the high pressure side (H) of the inner peripheralring 3100 to a sufficient extent.

In order to achieve this, it is only necessary to make the range ofmovement in the axial direction of the inner peripheral ring 3100 widerthan the axial width of the inner peripheral ring 3100 in its mounted orfitted state, as shown in FIG. 55 and FIG. 56. As a result of this,there will be a gap between the inner peripheral ring 3100 and theposition limiting ring 3500, so it will become possible to cause thefluid pressure to act on the high pressure side (H) of the innerperipheral ring 3100 to a sufficient extent.

However, from the point of view of stabilizing the pushing position ofthe inner peripheral ring 3100 with respect to the outer peripheral ring2000, it is preferable to make the range of movement in the axialdirection of the inner peripheral ring 3100 narrow. If possible, it ispreferable for the inner peripheral ring 3100 not to move in the axialdirection.

Accordingly, it can also be constructed such that the width (thedistance or length in the axial direction) of the position limiting ring3510 is made wide, as shown in FIG. 57, so that the position limitingring 3510 is always in abutment with a surface of the inner peripheralring 3100 at the high pressure side (H), thereby making it impossible ordifficult for the inner peripheral ring 3100 to move in the axialdirection.

In cases where such a construction is adopted, it is preferable to forma plurality of notches 3511 in the circumferential direction on a sidesurface of the position limiting ring 3510 at the low pressure side (L).According to this, a flow passage is ensured, as shown by an arrow X inFIG. 57, so it becomes possible to cause the fluid pressure to act onthe high pressure side (H) of the inner peripheral ring 3100 to asufficient extent. Here, note that FIG. 57 shows a state in which theengine is operated, and the fluid pressure in the right-hand side regionof the sealing device 1000 has become higher in comparison with that inthe left-hand side region of the sealing device 1000. In addition, FIG.58 is a part of a view when looking at the position limiting ring 3510from an outer peripheral surface side thereof, and FIG. 59 is a crosssectional view along a line A-A in FIG. 58.

Sixth Reference Example Summary

A sealing device according to a sixth reference example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side; and whereinsaid outer peripheral ring is formed on its inner peripheral surfaceside and at the low pressure side with an inner peripheral convexportion which is constructed so as to extend toward the inner peripheralsurface side, and which, at the time of holding the fluid pressure, ispushed by said inner peripheral ring into intimate contact with the sidewall surface at the low pressure side in said annular groove.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, the inner peripheral convex portion formed on the outerperipheral ring is pushed by the inner peripheral ring into intimatecontact with the side wall surface at the low pressure side in theannular groove. Accordingly, the outer peripheral ring is held in astate of intimate contact with the side wall surface at the low pressureside in the annular groove in a stable manner, so that the posture ofthe outer peripheral ring can be stabilized.

In addition, it is preferable that a position limiting ring to limitmovement of said inner peripheral ring toward the high pressure side befitted in said annular groove at the high pressure side and at an innerperipheral surface side inner than said outer peripheral ring.

According to this, the position of the inner peripheral ring is limitedor restricted, thereby making it possible to stabilize the posture ofthe outer peripheral ring to a further extent.

In addition, a sealing device according to the sixth reference exampleof the present disclosure, which is fitted into an annular groove formedin an outer periphery of a shaft so as to seal an annular gap betweensaid shaft and a housing which rotate relative to each other, thereby tohold a fluid pressure in a region to be sealed which is constructed suchthat the fluid pressure therein changes, comprising: an outer peripheralring made of resin that is in intimate contact with a side wall surfaceof said annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; an inner peripheral ring made of arubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; and aposition limiting ring that is fitted in said annular groove at the highpressure side and at an the inner peripheral surface side inner thansaid outer peripheral ring, and limits movement of said inner peripheralring toward the high pressure side; wherein said outer peripheral ringis formed on its outer peripheral surface with a concave portion whichextends from an end of a high pressure side to a position which does notarrive at an end of a low pressure side, so as to introduce fluidthereinto from the high pressure side.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, the movement of the inner peripheral ring toward the highpressure side is limited by means of the position limiting ring. As aresult of this, it is possible to suppress the pushing position of theinner peripheral ring with respect to the outer peripheral ring frombeing biased toward the high pressure side, i.e., toward a side in theouter peripheral surface at which the concave portion is formed.Accordingly, it is possible to stabilize the posture of the outerperipheral ring.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thesixth reference example of the present disclosure will be explainedwhile referring to FIG. 60 and FIG. 61. In this reference example, thereis shown a construction in which the position limiting ring shown in theabove-mentioned fifth reference example is provided with respect to thesealing device and the sealing structure which are shown in theabove-mentioned fourth reference example. Here, note that the samecomponent parts as those of the fourth reference example and the fifthreference example are denoted by the same reference numerals andcharacters, and the explanation thereof is omitted.

FIG. 60 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the sixth reference example of thepresent disclosure, and FIG. 61 is a schematic cross sectional viewshowing a high pressure state in the sealing device according to thesixth reference example of the present disclosure.

A sealing device 1000 according to this reference example is providedwith an outer peripheral ring 2000 made of resin, an inner peripheralring 3100 made of a rubber-like elastic body, and a position limitingring 3500. With respect to the outer peripheral ring 2000 and the innerperipheral ring 3100, their construction is the same as that explainedin the above-mentioned fourth reference example, and so, the detailedexplanation thereof is omitted. In addition, with respect to theposition limiting ring 3500, its construction is the same as thatexplained in the above-mentioned fifth reference example, so theexplanation thereof is omitted.

Thus, the sealing device 1000 according to this reference example has aconstruction in which the position limiting ring 3500 explained in theabove-mentioned fifth reference example is added to the sealing deviceand the sealing structure shown in the above-mentioned fourth referenceexample.

With the construction as mentioned above, in this reference example, thesame operational effects as in the case of the above-mentioned fourthreference example can be obtained, and in addition to this, the sameoperational effects as in the case of the above-mentioned fifthreference example can also be obtained.

Here, note that in this reference example, too, the position limitingring 3510 shown in the above-mentioned fifth reference example can beadopted. In this case, the inner peripheral ring 3100 is in a state ofbeing sandwiched between the position limiting ring 3510 and the innerperipheral convex portion 2312, so that it is not moved in the axialdirection.

Seventh Reference Example Summary

A sealing device according to a seventh reference example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side; and whereinsaid outer peripheral ring is formed on its inner peripheral surfaceside and at the low pressure side with an inner peripheral convexportion which is constructed so as to extend toward the inner peripheralsurface side, and which, at the time of holding the fluid pressure, ispushed by said inner peripheral ring into intimate contact with the sidewall surface at the low pressure side in said annular groove.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, the inner peripheral convex portion formed on the outerperipheral ring is pushed by the inner peripheral ring into intimatecontact with the side wall surface at the low pressure side in theannular groove. Accordingly, the outer peripheral ring is held in astate of intimate contact with the side wall surface at the low pressureside in the annular groove in a stable manner, so that the posture ofthe outer peripheral ring can be stabilized.

In addition, it is preferable that a position limiting ring to limitmovement of said inner peripheral ring toward the high pressure side befitted in said annular groove at the high pressure side and at an innerperipheral surface side inner than said outer peripheral ring.

According to this, the position of the inner peripheral ring is limitedor restricted, thereby making it possible to stabilize the posture ofthe outer peripheral ring to a further extent.

In addition, a sealing device according to the seventh reference exampleof the present disclosure, which is fitted into an annular groove formedin an outer periphery of a shaft so as to seal an annular gap betweensaid shaft and a housing which rotate relative to each other, thereby tohold a fluid pressure in a region to be sealed which is constructed suchthat the fluid pressure therein changes, comprising: an outer peripheralring made of resin that is in intimate contact with a side wall surfaceof said annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; an inner peripheral ring made of arubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; and aposition limiting ring that is fitted in said annular groove at the highpressure side and at an the inner peripheral surface side inner thansaid outer peripheral ring, and limits movement of said inner peripheralring toward the high pressure side; wherein said outer peripheral ringis formed on its outer peripheral surface with a concave portion whichextends from an end of a high pressure side to a position which does notarrive at an end of a low pressure side, so as to introduce fluidthereinto from the high pressure side.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, the movement of the inner peripheral ring toward the highpressure side is limited by means of the position limiting ring. As aresult of this, it is possible to suppress the pushing position of theinner peripheral ring with respect to the outer peripheral ring frombeing biased toward the high pressure side, i.e., toward a side in theouter peripheral surface at which the concave portion is formed.Accordingly, it is possible to stabilize the posture of the outerperipheral ring.

Specific Example

Hereinafter, a sealing device and a sealing structure according to theseventh reference example of the present disclosure will be explainedwhile referring to FIG. 62 and FIG. 63. In this reference example, thereis shown a construction in which in the sealing device and the sealingstructure shown in the above-mentioned sixth reference example, asurface of the inner peripheral convex portion at the high pressure sideis formed into or replaced by an inclined surface. Here, note that thesame component parts as those in the above-mentioned fourth referenceexample, the above-mentioned fifth reference example and theabove-mentioned sixth reference example are denoted by the samereference numerals and characters, and the explanation thereof isomitted.

FIG. 62 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the seventh reference example of thepresent disclosure, and FIG. 63 is a schematic cross sectional viewshowing a high pressure state in the sealing device according to theseventh reference example of the present disclosure.

A sealing device 1000 according to this reference example is providedwith an outer peripheral ring 2000 made of resin, an inner peripheralring 3100 made of a rubber-like elastic body, and a position limitingring 3500. With respect to the inner peripheral ring 3100, itsconstruction is the same as that explained in the above-mentioned fourthreference example, and so, the detailed explanation thereof is omitted.In addition, with respect to the position limiting ring 3500, itsconstruction is the same as that explained in the above-mentioned fifthreference example, so the explanation thereof is omitted.

Then, the outer peripheral ring 2000 according to this reference exampleis different from the outer peripheral ring shown in the above-mentionedfourth reference example in that a surface in the inner peripheralconvex portion 2313 at a high pressure side (H) is composed of aninclined surface which approaches to a low pressure side (L) as it goesto a groove bottom of an annular groove 4100. The other construction isthe same as the construction of the outer peripheral ring shown in theabove-mentioned fourth reference example, so the explanation thereof isomitted.

Thus, the sealing device 1000 according to this reference example has aconstruction in which the position limiting ring 3500 explained in theabove-mentioned fifth reference example is added to the sealing deviceand the sealing structure shown in the above-mentioned fourth referenceexample, after changing the construction of the inner peripheral convexportion in the outer peripheral ring. In other words, the sealing device1000 according to this reference example has a construction in which inthe sealing device and the sealing structure shown in theabove-mentioned sixth reference example, the surface of the innerperipheral convex portion at the high pressure side is formed into orreplaced by an inclined surface.

With the construction as mentioned above, in this reference example,too, similar to the case of the above-mentioned sixth reference example,the same operational effects as in the case of the above-mentionedfourth reference example can be obtained, and in addition to this, thesame operational effects as in the case of the above-mentioned fifthreference example can also be obtained. In addition, in this referenceexample, the surface in the inner peripheral convex portion 2313 at thehigh pressure side (H) is composed of the inclined surface whichapproaches to the low pressure side (L) as it goes to the groove bottomof the annular groove 4100. Accordingly, when the outer peripheral ring2000 is fitted into the annular groove 4100 after the inner peripheralring 3100 and the position limiting ring 3500 are mounted thereon, theinner peripheral convex portion 2313 easily enters between the innerperipheral ring 3100 and the side wall surface of the annular groove4100 at the low pressure side (L), so mountability (easiness of fitting)can be improved.

Here, note that in this reference example, too, the position limitingring 3510 shown in the above-mentioned fifth reference example can beadopted. In this case, the inner peripheral ring 3100 is in a state ofbeing sandwiched between the position limiting ring 3510 and the innerperipheral convex portion 2313, so that it is not moved in the axialdirection.

Eighth Reference Example Summary

In addition, a sealing structure according to an eighth referenceexample of the present disclosure, which is provided with: a shaft and ahousing that rotate relative to each other; and a sealing device that isfitted into an annular groove formed in an outer periphery of said shaftso as to seal an annular gap between said shaft and said housing,thereby to hold a fluid pressure in a region to be sealed which isconstructed such that the fluid pressure therein changes; said annulargroove being composed of a stepped groove of which an outside diameteris smaller at a low pressure side in comparison with at a high pressureside; said sealing device comprises: an outer peripheral ring made ofresin that is in intimate contact with a side wall surface of saidannular groove at a low pressure side thereof, and slides with respectto an inner peripheral surface of a shaft hole in said housing throughwhich said shaft is inserted; and an inner peripheral ring made of arubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a low pressure sideportion of a groove bottom surface of said annular groove of which theoutside diameter is small, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; andsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side.

According to the sealing structure according to this reference example,the following advantages are achieved in comparison with the sealingstructure explained in the above-mentioned embodiment. That is, in thisreference example, the inner peripheral ring is constructed such that itis in intimate contact with a low pressure side portion of the groovebottom surface of the annular groove composed of the stepped groove inwhich the outside diameter is small. With this construction, themovement of the inner peripheral ring toward the high pressure side isrestricted or limited by the stepped portion in the annular groove. Forthat reason, it is possible to suppress the pushing position of theinner peripheral ring with respect to the outer peripheral ring frombeing biased toward the high pressure side, i.e., toward a side in theouter peripheral surface at which the concave portion is formed.Accordingly, it is possible to stabilize the posture of the outerperipheral ring.

It is preferable that said outer peripheral ring be formed on its innerperipheral surface side and at the low pressure side with an innerperipheral convex portion which is constructed so as to extend towardthe inner peripheral surface side, and which, at the time of holding thefluid pressure, is pushed by said inner peripheral ring into intimatecontact with the side wall surface at the low pressure side in saidannular groove.

According to this, the outer peripheral ring is held in a state ofintimate contact with the side wall surface at the low pressure side inthe annular groove in a stable manner, so that the posture of the outerperipheral ring can be stabilized.

Specific Example

Hereinafter, a sealing device and a sealing structure according to theeighth reference example of the present disclosure will be explainedwhile referring to FIG. 64 and FIG. 65. In this reference example, thereis shown a case in which with respect to the sealing device and thesealing structure shown in the above-mentioned fifth reference example,the annular groove is composed of a stepped groove, instead of theprovision of the position limiting ring. The other construction andoperation of this example are the same as those in the above-mentionedfifth reference example, and hence, the same component parts as those ofthe above-mentioned fifth reference example are denoted by the samereference numerals and characters, and the explanation thereof isomitted.

FIG. 64 is a schematic cross sectional view showing an unloaded state inthe sealing device according to the eighth reference example of thepresent disclosure, and FIG. 65 is a schematic cross sectional viewshowing a high pressure state in the sealing device according to theeighth reference example of the present disclosure.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 and an inner peripheral ring 3100. Theconstruction of these component parts are the same as the outerperipheral ring and the inner peripheral ring in the above-mentionedfifth reference example.

Then, in this reference example, an annular groove 4110 formed in ashaft 4000 is composed of a stepped groove of which the outside diameteris smaller at a low pressure side (L) in comparison with a high pressureside (H). In addition, the inner peripheral ring 3100 is arranged suchthat it is in intimate contact with an inner peripheral surface in theouter peripheral ring 2000 and that portion of a groove bottom surfaceof the annular groove 4110 which is at the low pressure side (L) and ofwhich the outside diameter is small, respectively.

With the construction as mentioned above, a large diameter portion atthe high pressure side (H) in the annular groove 4110 composed of thestepped groove exhibits the same function as that of the positionlimiting ring 3500 in the above-mentioned fifth reference example. Thatis, the movement of the inner peripheral ring 3100, which is arranged inthe small diameter portion at the low pressure side (L), toward the highpressure side (H) is restricted or limited by the stepped portion in theannular groove 4110. From the above, in this reference example, too, thesame effects as in the case of the above-mentioned fifth referenceexample can be obtained.

Here, note that in this reference example, too, the width (i.e., thedistance or length in the axial direction) of the large diameter portionin the annular groove 4110 may be made wide, as in the case of theposition limiting ring 3510 shown in the above-mentioned fifth referenceexample. According to this, by making the stepped portion in the annulargroove 4110 always in abutment with a surface of the inner peripheralring 3100 at the high pressure side (H), it becomes possible to make itimpossible or difficult for the inner peripheral ring 3100 to move inthe axial direction. In cases where such a construction is adopted, itis preferable to form a plurality of notches in the circumferentialdirection on a side surface in the stepped portion at the low pressureside (L) as in the case of the position limiting ring 3510. According tothis, a flow passage is ensured, as in case of the position limitingring 3510, so it becomes possible to cause the fluid pressure to act onthe high pressure side (H) of the inner peripheral ring 3100 to asufficient extent.

Here, note that in this reference example, as an example of the outerperipheral ring 2000, there has been shown a construction in the case ofan inner peripheral convex portion being not formed, as shown in thefifth reference example, but there may instead be used the outerperipheral ring 2000 which is provided with the inner peripheral convexportion 2312 or 2313, as shown in the fourth, the sixth and the seventhreference example.

Ninth Reference Example Summary

A sealing structure according to a ninth reference example of thepresent disclosure, which is provided with: a shaft and a housing thatrotate relative to each other; and a sealing device that is fitted intoan annular groove formed in an outer periphery of said shaft so as toseal an annular gap between said shaft and said housing, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes; wherein an annular concave portionconcaved to a low pressure side is formed in a side wall surface of saidannular groove at the low pressure side at a location nearer to a groovebottom side than to an outer peripheral surface of said shaft; saidsealing device comprises: an outer peripheral ring made of resin that isin intimate contact with that portion of the side wall surface of saidannular groove at the low pressure side in which said annular concaveportion is not formed, and slides with respect to an inner peripheralsurface of a shaft hole in said housing through which said shaft isinserted; and an inner peripheral ring made of a rubber-like elasticbody that is in intimate contact with an inner peripheral surface ofsaid outer peripheral ring and a groove bottom surface of said annulargroove, respectively, thereby to push said outer peripheral ring towardan outer peripheral surface side thereof; said outer peripheral ring isformed on its outer peripheral surface with a concave portion whichextends from an end of a high pressure side to a position which does notarrive at an end of a low pressure side, so as to introduce fluidthereinto from the high pressure side, and said outer peripheral ring isalso formed on an inner peripheral surface side of its side surface atthe low pressure side with a protrusion portion which comes into saidannular concave portion; and said inner peripheral ring is arranged soas to be able to be in intimate contact with a side wall surface of saidannular concave portion at the low pressure side.

In addition, a sealing device according to the ninth reference exampleof the present disclosure, which is fitted into an annular groove formedin an outer periphery of a shaft so as to seal an annular gap betweensaid shaft and a housing which rotate relative to each other, thereby tohold a fluid pressure in a region to be sealed which is constructed suchthat the fluid pressure therein changes, said annular groove having anannular concave portion formed so as to be concave to a low pressureside in a position nearer to a groove bottom side than to an outerperipheral surface of said shaft, comprising: an outer peripheral ringmade of resin that is in intimate contact with that portion of the sidewall surface of said annular groove at the low pressure side in whichsaid annular concave portion is not formed, and slides with respect toan inner peripheral surface of a shaft hole in said housing throughwhich said shaft is inserted; and an inner peripheral ring made of arubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side, and saidouter peripheral ring is also formed on an inner peripheral surface sideof its side surface at the low pressure side with a protrusion portionwhich comes into said annular concave portion; and wherein said innerperipheral ring is arranged so as to be able to be in intimate contactwith a side wall surface of said annular concave portion at the lowpressure side.

According to the sealing structure and the sealing device according tothis reference example, the following advantages are achieved incomparison with the sealing structure and the sealing device explainedin the above-mentioned embodiment. That is, in this reference example,the annular concave portion is formed on the side wall surface of theannular groove at the low pressure side, and the protrusion portion,which comes into this annular concave portion, is formed on the sidesurface of the outer peripheral ring at the low pressure side. Inaddition, the inner peripheral ring is arranged so as to be able to bein intimate contact with the side wall surface of the annular concaveportion at the low pressure side. For that reason, it becomes possibleto cause the position of intimate contact of the inner peripheral ringwith respect to the outer peripheral ring to be biased to the lowpressure side. As a result of this, it becomes possible to make theposition in which the outer peripheral ring slides with respect to theinner peripheral surface of the shaft hole, and the positions in whichthe inner peripheral ring is in intimate contact with respect to theinner peripheral surface of the outer peripheral ring and the groovebottom surface of the annular groove, respectively, close to (desirablycoincident with) each other in the axial direction. Accordingly, it ispossible to suppress the outer peripheral ring from being inclined inthe annular groove, thereby making it possible to stabilize the mountingstate of the outer peripheral ring.

Specific Example

Hereinafter, a sealing device and a sealing structure according to theninth reference example of the present disclosure will be explained morespecifically while referring to FIG. 66 through FIG. 70. Here, note thatthe basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts are denoted bythe same reference numerals and characters, and the explanation thereofis omitted as the case may be.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this reference example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O ring, but as such there can be adopted otherseal ring such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Annular Groove>

The construction of an annular groove 4120 formed on an outer peripheryof a shaft 4000 will be explained in further detail while referring inparticular to FIG. 69 and FIG. 70. On a side wall surface of the annulargroove 4120 at a low pressure side (L) according to this referenceexample, there is formed an annular concave portion 4121 which isconcaved to the low pressure side (L) at a location nearer to a groovebottom side than to an outer peripheral surface of the shaft 4000. Inaddition, by the formation of the annular concave portion 4121, anannular convex portion 4122 projected to a high pressure side (H) isformed on the side wall surface of the annular groove 4120 at the lowpressure side (L) in the vicinity of the outer peripheral surface of theshaft 4000.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this ninth reference exampleof the present disclosure will be explained in further detail whilereferring in particular to FIG. 66 through FIG. 68. An abutment jointportion 2100 is formed on the outer peripheral ring 2000 at one place ina circumferential direction thereof. In addition, the outer peripheralring 2000 is formed on its outer peripheral surface with a concaveportion 2220 for introducing fluid. Furthermore, a protrusion portion2400 is formed on a side surface in the outer peripheral ring 2000 at aside opposite to a side at which the concave portion 2220 is formed.

Here, note that the outer peripheral ring 2000 according to thisreference example is constructed such that the abutment joint portion2100, the concave portion 2220 and the protrusion portion 2400 asmentioned above are formed on an annular member of which the crosssection is rectangular. However, this is only an explanation of theshape thereof, but does not necessarily mean that an annular member of arectangular cross section is used as a material, and processing to formthe abutment joint portion 2100, the concave portion 2220 and theprotrusion portion 2400 is applied to this material. Of course, after anannular member of a rectangular cross section has been molded or formed,the abutment joint portion 2100, the concave portion 2220 and theprotrusion portion 2400 can also be obtained by means of cutting work.However, for example, after molding or forming a member which has theabutment joint portion 2100 in advance, the concave portion 2220 and theprotrusion portion 2400 may be obtained by means of cutting work. Inthis manner, the method of production thereof is not limited inparticular.

A special step cut is employed for the abutment joint portion 2100,similar to the above-mentioned embodiment. However, for the abutmentjoint portion 2100, there can be adopted a straight cut, a bias cut,another step cut, and so on, including but not limited to this. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100.

In this reference example, too, the concave portion 2220 is formed overthe entire periphery of the outer peripheral ring 2000 except for thevicinity of the abutment joint portion 2100. The concave portion 2220 isthe same as explained in the above-mentioned embodiment, and so, thedetailed explanation thereof is omitted.

In addition, in this reference example, the protrusion portion 2400 isformed over the entire periphery of the outer peripheral ring 2000except for the vicinity of the abutment joint portion 2100. Thisprotrusion portion 2400 is formed on an inner peripheral surface side ofthe side surface of the outer peripheral ring 2000 at the low pressureside (L). Then, this protrusion portion 2400 is constructed so as tocome into the annular concave portion 4121 formed in the annular groove4120.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis reference example will be explained, while referring in particularto FIG. 69 and FIG. 70. FIG. 69 shows an unloaded state in which anengine is stopped, and there does not exist a differential pressure (orthere exists substantially no differential pressure) between right-handside region of the sealing device 1000 and left-hand side region of thesealing device 1000. FIG. 70 shows a state in which the engine isoperated, and fluid pressure in the right-hand side region of thesealing device 1000 has become higher in comparison with that in theleft-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in the annular groove4120, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4120, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portion 2220 (i.e., a low pressure side convexportion 2210 and a portion of the outer peripheral ring 2000 in thevicinity of the abutment joint portion 2100 in which the concave portion2220 is not formed) maintain a state in which they are in contact withthe inner peripheral surface of the shaft hole in the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed by meansof the fluid pressure from the high pressure side (H), so that itbecomes a state of being in intimate contact with the annular convexportion 4122 in the side wall surface of the annular groove 4120 at thelow pressure side (L), as shown in FIG. 70. Here, note that it isneedless to say that the outer peripheral ring 2000 maintains the stateof being in contact (sliding) with the inner peripheral surface of theshaft hole in the housing 5000. In addition, with respect to the innerperipheral ring 3100, it becomes a state of being in intimate contactwith the annular concave portion 4121 in the side wall surface of theannular groove 4120 at the low pressure side (L).

In addition, in this reference example, there is adopted a constructionin which the protrusion portion 2400 formed on the outer peripheral ring2000 comes into the annular concave portion 4121 formed in the annulargroove 4120. According to this, it is made possible to cause theposition of intimate contact of the inner peripheral ring 3100 withrespect to the outer peripheral ring 2000 to be biased to the lowpressure side (L). Here, note that in this reference example, in a statewhere the inner peripheral ring 3100 is in intimate contact with theannular concave portion 4121, a region of a seal portion S1 between theouter peripheral ring 2000 and the shaft hole inner peripheral surface,a region of a seal portion S2 between the inner peripheral ring 3100 andthe outer peripheral ring 2000 and a region of a seal portion S3 betweenthe inner peripheral ring 3100 and the groove bottom of the annulargroove 4120 are designed in such a manner that at least parts thereofoverlap with each other, in the case of being viewed in a radialdirection in any of a no-load condition and a high pressure condition(refer to FIG. 69 and FIG. 70).

<Advantages of the Sealing Device and the Sealing Structure According tothis Reference Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, the annularconcave portion 4121 is formed on the side wall surface of the annulargroove 4120 at the low pressure side (L), and the protrusion portion2400, which comes into this annular concave portion 4121, is formed onthe side surface of the outer peripheral ring 2000 at the low pressureside (L). In addition, the inner peripheral ring 3100 is arranged so asto be able to be in intimate contact with the side wall surface of theannular concave portion 4121 at the low pressure side (L). For thatreason, it becomes possible to cause the position of intimate contact ofthe inner peripheral ring 3100 with respect to the outer peripheral ring2000 to be biased to the low pressure side (L). As a result of this, itbecomes possible to make the position (the seal portion S1) in which theouter peripheral ring 2000 slides with respect to the inner peripheralsurface of the shaft hole, the position (the seal portion S2) in whichthe inner peripheral ring 3100 is in intimate contact with respect tothe inner peripheral surface of the outer peripheral ring 2000, and theposition (the seal portion S3) in which the inner peripheral ring 3100is in intimate contact with respect to the groove bottom surface of theannular groove 4120 close to each other in the axial direction. In thisreference example, as mentioned above, in a state where the innerperipheral ring 3100 is in intimate contact with the annular concaveportion 4121, the region of the seal portion S1, the region of the sealportion S2 and the region of the seal portion S3 are designed in such amanner that at least parts thereof overlap with each other when viewedin the radial direction, in any of the no-load condition and the highpressure condition. Accordingly, it is possible to suppress the outerperipheral ring 2000 from being inclined in the annular groove 4120,thereby making it possible to stabilize the mounting state of the outerperipheral ring 2000.

(Others)

In this reference example, there is shown a construction in which theprotrusion portion 2400 is formed over the entire periphery of the outerperipheral ring 2000 except for the vicinity of the abutment jointportion 2100. However, with respect to the protrusion portion 2400,there can be adopted another construction in which a plurality ofprotrusion portions are provided at a predetermined distance spacedapart from one another in a circumferential direction.

Tenth Reference Example Summary

A sealing device according to a tenth reference example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with saidouter peripheral ring and said annular groove, respectively; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side, and alsowith an inclined surface which connects a side wall surface at a highpressure side and its inner peripheral surface with each other; andwherein said inner peripheral ring is in intimate contact with saidinclined surface in said outer peripheral ring, a groove bottom surfaceand the side wall surface at the high pressure side in said annulargroove, respectively, thereby to push said outer peripheral ring towardits outer peripheral surface side and the low pressure side.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, the outer peripheral ring is pushed toward its outer peripheralsurface side and the low pressure side by means of the inner peripheralring which is constructed so as to be in intimate contact with theinclined surface. Accordingly, the outer peripheral ring is kept in astate of being in intimate contact with the inner peripheral surface ofthe shaft hole in the housing and the side wall surface of the annulargroove at the low pressure side, so that a stable posture thereof ismaintained without regard to a change in the fluid pressure. As a resultof this, a sealing function is maintained in a stable manner. Further,invasion of fluid from the high pressure side to the inner peripheralsurface side of the outer peripheral ring can be suppressed by means ofthe inner peripheral ring which is in intimate contact with the inclinedsurface in the outer peripheral ring, the groove bottom surface and theside wall surface at the high pressure side in the annular groove,respectively. According to this, it is possible to suppress an increaseof a pushing force toward the outer peripheral surface side of the outerperipheral ring accompanying the increase in the fluid pressure, whichis combined with the above-mentioned effect due to the concave portion,thereby making it possible to suppress an increase in sliding torque ina synergistic manner.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thetenth reference example of the present disclosure will be explained morespecifically while referring to FIG. 71 through FIG. 75. Here, note thatthe basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts are denoted bythe same reference numerals and characters, and the explanation thereofis omitted as the case may be.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this reference example is a so-called O ring having acircular cross sectional shape.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this tenth reference exampleof the present disclosure will be explained in further detail whilereferring in particular to FIG. 71 through FIG. 73. An abutment jointportion 2100 is formed on the outer peripheral ring 2000 at one place ina circumferential direction thereof. In addition, the outer peripheralring 2000 is formed on its outer peripheral surface with a concaveportion 2220 for introducing fluid. Further, the outer peripheral ring2000 is formed with an inclined surface 2323 which connects its sidewall surface at a high pressure side and its inner peripheral surfacewith each other. Although the inclined surface 2323 according to thisreference example is a tapered surface, it may be composed of a curvedsurface which becomes a curved line when viewed in cross section.

Here, note that the outer peripheral ring 2000 according to thisreference example is constructed such that the abutment joint portion2100, the concave portion 2220 and the inclined surface 2323 asmentioned above are formed on an annular member of which the crosssection is rectangular. However, this is only an explanation of theshape thereof, but does not necessarily mean that an annular member of arectangular cross section is used as a material, and processing to formthe abutment joint portion 2100, the concave portion 2220 and theinclined surface 2323 is applied to this material. Of course, after anannular member of a rectangular cross section has been molded or formed,the abutment joint portion 2100, the concave portion 2220 and theinclined surface 2323 can also be obtained by means of cutting work.However, for example, after molding or forming a member which has theabutment joint portion 2100 in advance, the concave portion 2220 and theinclined surface 2323 may be obtained by means of cutting work. In thismanner, the method of production thereof is not limited in particular.

A special step cut is employed for the abutment joint portion 2100,similar to the above-mentioned embodiment. However, for the abutmentjoint portion 2100, there can be adopted a straight cut, a bias cut,another step cut, and so on, including but not limited to this. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100.

In this reference example, too, the concave portion 2220 is formed overthe entire periphery of the outer peripheral ring 2000 except for thevicinity of the abutment joint portion 2100. The concave portion 2220 isthe same as explained in the above-mentioned embodiment, and so, thedetailed explanation thereof is omitted.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis reference example will be explained, while referring in particularto FIG. 74 and FIG. 75. FIG. 74 shows an unloaded state in which anengine is stopped, and there does not exist a differential pressure (orthere exists substantially no differential pressure) between right-handside region of the sealing device 1000 and left-hand side region of thesealing device 1000. FIG. 75 shows a state in which the engine isoperated, and fluid pressure in the right-hand side region of thesealing device 1000 has become higher in comparison with that in theleft-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in an annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inclined surface 2323 in the outerperipheral ring 2000 and a groove bottom surface and a side wall surfaceat a high pressure side (H) in the annular groove 4100, respectively.According to this, the inner peripheral ring 3100 exhibits a function ofpushing the outer peripheral ring 2000 toward its outer peripheralsurface side and a low pressure side (L) due to the elastic repulsionthereof.

Here, as shown in FIG. 74, in an unloaded condition, too, the outerperipheral ring 2000 is pushed toward its outer peripheral surface sideand the low pressure side (L) by means of the inner peripheral ring3100, as mentioned above. Accordingly, those portions of the outerperipheral surface of the outer peripheral ring 2000 which exclude theconcave portion 2220 (i.e., a low pressure side convex portion 2210 anda portion of the outer peripheral ring 2000 in the vicinity of theabutment joint portion 2100 in which the concave portion 2220 is notformed) maintain a state in which they are in contact with the innerperipheral surface of the shaft hole in the housing 5000 and the sidewall surface of the annular groove 4100 at the low pressure side (L).

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 becomes a state ofbeing further pushed to the low pressure side (L) by means of the fluidpressure from the high pressure side (H), as shown in FIG. 75. Thus, inthe state in which differential pressure has been generated, too, theouter peripheral ring 2000 maintains its state of being in intimatecontact with respect to the side wall surface of the annular groove 4100at the low pressure side (L), and at the same time maintains its stateof being in contact (sliding contact) with respect to the innerperipheral surface of the shaft hole in the housing 5000. In addition,with respect to the inner peripheral ring 3100, too, it also maintains astate of being in intimate contact with the inclined surface 2323 in theouter peripheral ring 2000, the groove bottom surface and the side wallsurface at the high pressure side (H) of the annular groove 4100,respectively.

<Advantages of the Sealing Device According to this Reference Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, the outerperipheral ring 2000 is pushed toward its outer peripheral surface sideand the low pressure side (L) by means of the inner peripheral ring 3100which is constructed so as to be in intimate contact with the inclinedsurface 2323. Accordingly, the outer peripheral ring 2000 is kept in astate of being in intimate contact with the inner peripheral surface ofthe shaft hole in the housing 5000 and the side wall surface of theannular groove 4100 at the low pressure side (L), so that a stableposture thereof is maintained without regard to a change in the fluidpressure. In other words, the concave portion 2220 is formed over a widerange of the outer peripheral surface of the outer peripheral ring 2000,and hence, if the inner peripheral ring 3100 is not provided, there willbe a fear that the outer peripheral ring 2000 may be inclined in acounter-clockwise direction in FIGS. 74 and 75. However, in thisreference example, as mentioned above, the outer peripheral ring 2000becomes a state of being pushed with respect to the inner peripheralsurface of the shaft hole in the housing 5000, and the side wall surfaceof the annular groove 4100 at the low pressure side (L), so that itsposture is stabilized. As a result, according to the sealing device 1000according to this reference example, a sealing function can bemaintained in a stable manner.

Here, note that in this reference example, too, the concave portion 2220is formed on the outer peripheral surface of the outer peripheral ring2000, so that fluid can be introduced into this concave portion 2220from the high pressure side (H). For that reason, even if the fluidpressure becomes higher, the fluid pressure acts toward the innerperipheral surface side of the outer peripheral ring 2000 in a region inwhich the concave portion 2220 is formed. Here, note that an arrow P1 inFIG. 75 shows how the fluid pressure acts with respect to the outerperipheral ring 2000. According to this, in the sealing device 1000according to this reference example, too, it is possible to suppress arise in pressure toward the outer peripheral surface side by means ofthe outer peripheral ring 2000 accompanying a rise in the fluidpressure, thus making it possible to suppress sliding torque to a lowlevel.

In addition, in this reference example, the inner peripheral ring 3100is in intimate contact with the inclined surface 2323 in the outerperipheral ring 2000, the groove bottom surface and the side wallsurface at the high pressure side (H) of the annular groove 4100,respectively, thereby exhibiting a sealing function in these intimatecontact portions. For that reason, it is possible to suppress invasionof the fluid from the high pressure side (H) to the inner peripheralsurface side of the outer peripheral ring 2000. According to this, it ispossible to suppress a rise in the pushing force to the outer peripheralsurface side of the outer peripheral ring 2000 accompanying a rise inthe fluid pressure at the high pressure side (H). In other words, evenif pressure P1 in FIG. 75 at the outer peripheral surface side goes upwith the rise of the fluid pressure, pressure P2 at the inner peripheralsurface side does not change so much. Accordingly, in combination withthe above-mentioned effect due to the concave portion 2220, this servesto suppress a rise in sliding torque in a synergistic manner.

Here, note that with respect to the feature that the outer peripheralring 2000 slides at the outer peripheral surface side thereof, it is thesame as in the case of the above-mentioned embodiment.

Eleventh Reference Example Summary

A sealing device according to an eleventh reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; andwherein said outer peripheral ring is formed on its outer peripheralsurface with a concave portion which extends from an end of a highpressure side to a position which does not arrive at an end of a lowpressure side, so as to introduce fluid thereinto from the high pressureside, in a state where said outer peripheral ring is fitted in a normaldirection; and wherein said outer peripheral ring is formed with apassage for detecting a fitting direction which forms a flow passagethrough which fluid to be sealed leaks from the high pressure side tothe low pressure side, in a state where said outer peripheral ring isfitted in a reverse direction.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, the outer peripheral ring is formed with the fitting directiondetection passage. Accordingly, in cases where the outer peripheral ringis fitted in a reverse direction, an amount of leakage of fluid to besealed increases, and hence, by measuring the amount of leakage, aconfirmation can be made as to whether the outer peripheral ring isfitted in a normal direction. In addition, in the case of the sealingdevice according to this reference example, too, the outer peripheralring is pushed toward the outer peripheral surface side thereof by meansof the inner peripheral ring. For that reason, even in a state where thefluid pressure does not act (differential pressure is not generated), orin a state where the fluid pressure does not substantially act(differential pressure is not substantially generated), the outerperipheral ring becomes the state of being in contact with the innerperipheral surface of the shaft hole in the housing, so that a sealingfunction is exhibited as long as the outer peripheral ring is inintimate contact with the side wall surface at the low pressure side inthe annular groove. Accordingly, the fluid pressure can be made to beheld from immediately after the fluid pressure in the region to besealed begins to increase.

Here, it is preferable that said fitting direction detection passage becomposed of a first groove that is formed on the inner peripheralsurface side of said outer peripheral ring so as to extend in an axialdirection, and a second groove that is formed on a side wall surfaceside of said outer peripheral ring at the low pressure side in a statewhere said outer peripheral ring is fitted in the reverse direction, andextends in a radial direction so as to be connected with the firstgroove.

Specific Example

Hereinafter, a sealing device and a sealing structure according to theeleventh reference example of the present disclosure will be explainedmore specifically while referring to FIG. 76 through FIG. 82. Here, notethat the basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts are denoted bythe same reference numerals and characters, and the explanation thereofis omitted as the case may be.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this reference example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O ring, but as such there can be adopted otherseal ring such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this reference example ofthe present disclosure will be explained in further detail whilereferring in particular to FIG. 76 through FIG. 79. An abutment jointportion 2100 is formed on the outer peripheral ring 2000 at one place ina circumferential direction thereof. In addition, the outer peripheralring 2000 is formed on its outer peripheral surface with a concaveportion 2220 for introducing fluid. Further, the outer peripheral ring2000 is formed on its inner peripheral surface and its side wall surfacewith a first groove 2324 and a second groove 2420, respectively, whichtogether constitute a fitting direction detection passage.

Here, note that the outer peripheral ring 2000 according to thisreference example is constructed such that the abutment joint portion2100, the concave portion 2220, the first groove 2324 and the secondgroove 2420 as mentioned above are formed on an annular member of whichthe cross section is rectangular. However, this is only an explanationof the shape thereof, but does not necessarily mean that an annularmember of a rectangular cross section is used as a material, andprocessing to form the abutment joint portion 2100, the concave portion2220, the first groove 2324 and the second groove 2420 is applied tothis material. Of course, after an annular member of a rectangular crosssection has been molded or formed, the abutment joint portion 2100, theconcave portion 2220, the first groove 2324 and the second groove 2420can also be obtained by means of cutting work. However, for example,after molding or forming a member which has the abutment joint portion2100 in advance, the concave portion 2220, the first groove 2324 and thesecond groove 2420 may be obtained by means of cutting work. In thismanner, the method of production thereof is not limited in particular.

A special step cut is employed for the abutment joint portion 2100,similar to the above-mentioned embodiment. However, for the abutmentjoint portion 2100, there can be adopted a straight cut, a bias cut,another step cut, and so on, including but not limited to this. Inaddition, in cases where a material (e.g., PTFE, etc.) of low elasticityis adopted as a material of the outer peripheral ring 2000, the outerperipheral ring 2000 may also be endless, without forming the abutmentjoint portion 2100.

In this reference example, too, the concave portion 2220 is formed overthe entire periphery of the outer peripheral ring 2000 except for thevicinity of the abutment joint portion 2100. The concave portion 2220 isthe same as explained in the above-mentioned embodiment, and so, thedetailed explanation thereof is omitted.

Then, the outer peripheral ring 2000 according to this reference exampleis formed with the fitting direction detection passage. This fittingdirection detection passage is composed of the first groove 2324 formedon the inner peripheral surface of the outer peripheral ring 2000, andthe second groove 2420 formed on the side wall surface. The first groove2324 is constructed so as to extend in the axial direction. Also, thesecond groove 2420 is constructed so as to extend in the radialdirection. This second groove 2420 is formed on the side wall surface atthe low pressure side (L) in a state where the outer peripheral ring2000 is incorrectly fitted in the reverse direction, as will bedescribed later. Then, the first groove 2324 and the second groove 2420are constructed so as to be connected with each other.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis reference example will be explained, while referring in particularto FIG. 80 and FIG. 81. FIG. 80 shows an unloaded (or low load) state inwhich the engine is stopped, and there does not exist a differentialpressure (or there exists substantially no differential pressure)between right-hand side region of the sealing device 1000 and left-handside region of the sealing device 1000. FIG. 81 shows a state in whichthe engine is operated, and fluid pressure in the right-hand side regionof the sealing device 1000 has become higher in comparison with that inthe left-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in the annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portion 2220 (i.e., a low pressure side convexportion 2210 and a portion of the outer peripheral ring 2000 in thevicinity of the abutment joint portion 2100 in which the concave portion2220 is not formed) maintain a state in which they are in contact withthe inner peripheral surface of the shaft hole in the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed to thelow pressure side (L) by means of the fluid pressure from the highpressure side (H), so that it becomes a state of being in intimatecontact with the side wall surface of the annular groove 4100 at the lowpressure side (L), as shown in FIG. 81. Here, note that it is needlessto say that the outer peripheral ring 2000 maintains the state of beingin contact (sliding) with the inner peripheral surface of the shaft holein the housing 5000. In addition, with respect to the inner peripheralring 3100, too, it also becomes a state of being in intimate contactwith the side wall surface of the annular groove 4100 at the lowpressure side (L).

<Advantages of the Sealing Device According to this Reference Example>

According to the sealing device 1000 and sealing structure providedtherewith according to this reference example, the outer peripheral ring2000 is pushed toward the outer peripheral surface side thereof by meansof the inner peripheral ring 3100. For that reason, even in a statewhere the fluid pressure does not act (a differential pressure has notoccurred), or in a state where the fluid pressure does not substantiallyact (a differential pressure has not substantially occurred), the outerperipheral ring 2000 becomes the state of being in contact with theinner peripheral surface of the shaft hole in the housing 5000. Here,note that an annular continuous sealing surface is formed by an outerperipheral surface of the low pressure side convex portion 2210 in theouter peripheral ring 2000 and an outer peripheral surface of thatportion of the outer peripheral ring 2000 in which the concave portion2220 is not formed in the vicinity of the abutment joint portion 2100.For that reason, a sealing function is exhibited as long as the outerperipheral ring 2000 is in intimate contact with the side wall surfaceat the low pressure side (L) in the annular groove 4100. Accordingly,the fluid pressure can be made to be held from immediately after thefluid pressure in the region to be sealed begins to increase, as in thecase of the above-mentioned embodiment, individual reference examplesand individual practical examples.

Here, note that in a state where a considerable period of time haselapsed after the engine has been stopped, the fluid pressure ceases toact completely (i.e., differential pressure becomes zero). In this case,the outer peripheral ring 2000 can move away from the side wall surfaceof the annular groove 4100 (the side wall surface at the low pressureside (L) at the time of the generation of differential pressure). Forthat reason, in the case of the sealing device 1000 according to thisreference example, the first groove 2324 is formed on the innerperipheral surface of the outer peripheral ring 2000, and hence, leakageof fluid may occur. However, as mentioned above, in cases where thestopped state of the engine continues not so long, the state ofgeneration of differential pressure can be maintained, so that the outerperipheral ring 2000 can be maintained in intimate contact with the sidewall surface of the annular groove 4100 at the low pressure side (L).Accordingly, even under a low load condition, the function ofsuppressing the leakage of fluid is exhibited.

The operational effects due to the concave portion 2220 formed on theouter peripheral surface of the outer peripheral ring 2000 are asexplained in the above-mentioned embodiment.

Here, in the sealing device 1000 according to this reference example, incases where the outer peripheral ring 2000 is fitted in a properdirection (in a normal direction), the operational effects as mentionedabove are exhibited. In other words, in cases where the outer peripheralring 2000 is fitted in the annular groove 4100 in such a manner that thelow pressure side convex portion 2210 becomes the low pressure side (L)at the time of the generation of differential pressure, fluid isintroduced into the concave portion 2220, whereby the operationaleffects as mentioned above are exhibited. In cases where the outerperipheral ring 2000 is fitted in the reverse direction by mistake,fluid is not introduced into the concave portion 2220, so theoperational effects as stated above can not be obtained. In addition, ifthe outer peripheral ring 2000 has been fitted in the reverse direction,a low torque effect will not be obtained, but there will also be a fearthat sliding between the outer peripheral ring 2000 and the innerperipheral ring 3100 may be caused due to side surface sliding thereof,thereby giving rise to abnormal wear.

As a result, it is necessary to prevent the outer peripheral ring 2000from being fitted in the reverse direction. Accordingly, in the sealingdevice 1000 according to this reference example, it is devised such thata confirmation can be simply made as to whether the outer peripheralring 2000 has been fitted in the normal direction or in the reversedirection. This will be explained below with reference to FIG. 82. FIG.82 shows a state in which the outer peripheral ring 2000 has been fittedin the reverse direction by mistake, and the fluid pressure in aright-hand side region of the sealing device 1000 has become higher incomparison with that in a left-hand side region of the sealing device1000. In the sealing device 1000 according to this reference example,the fitting direction detection passage composed of the first groove2324 and the second groove 2420 is formed on the outer peripheral ring2000, as mentioned above. The outer peripheral ring 2000 in FIG. 82shows a cross section of a portion in which this fitting directiondetection passage is formed. In cases where the outer peripheral ring2000 is fitted in the reverse direction, there is formed a flow passagethrough which the fluid to be sealed leaks from the high pressure side(H) to the low pressure side (L), so that it first passes through thefirst groove 2324 (arrow A1), and then passes through the second groove2420 (arrow A2). Accordingly, by measuring an amount of leakage of fluidin a state where differential pressure has been generated, it becomespossible to simply make a confirmation as to whether the outerperipheral ring 2000 has been fitted in the normal direction or in thereverse direction.

Here, note that a leakage test was carried out under the condition thatthe cross-sectional area of the fitting direction detection passage(i.e., the cross-sectional areas of the first groove 2324 and the secondgroove 2420) was set to be about 30 mm²′ and the pressure of fluid(e.g., a gas such as air) at the high pressure side was set to be 1 MPaunder an environment of room temperature in a state where there was norelative rotation between the shaft 4000 and the housing 5000. As aresult of this leakage test, it was found that in cases where the outerperipheral ring 2000 is fitted in the normal direction, the amount ofleakage was 2 cc/min, but in contrast to this, in cases where the outerperipheral ring 2000 is fitted in the reverse direction, the amount ofleakage was 420 cc/min. Thus, due to the fact that a large differenceappears in the amount of leakage, it is possible to simply make aconfirmation as to whether the outer peripheral ring 2000 has beenfitted in the normal direction or in the reverse direction. Here, notethat in this reference example, there has been shown the construction inthe case where the fitting direction detection passage is formed only inone place, but a plurality of fitting direction detection passages maybe formed at locations which are different from one another in thecircumferential direction.

Twelfth Reference Example Summary

A sealing device according to a twelfth reference example of the presentdisclosure, which is fitted into an annular groove formed in an outerperiphery of a shaft so as to seal an annular gap between said shaft anda housing which rotate relative to each other, thereby to hold a fluidpressure in a region to be sealed which is constructed such that thefluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side; wherein anabutment joint portion is formed on said outer peripheral ring at oneplace in a circumferential direction thereof; wherein said abutmentjoint portion has an engagement convex portion which is formed at oneouter peripheral surface side of a cut portion and at a low pressureside surface side, and an engagement concave portion which is formed atthe other outer peripheral surface side and at the low pressure sidesurface side, and into which said engagement convex portion is engagedthereby to exhibit a sealing function in both an axial direction and aradial direction; and wherein between an end face of a portion of saidouter peripheral ring at the one side of said cut portion except forsaid engagement convex portion, and an end face of a portion of saidouter peripheral ring at the other side except for said engagementconcave portion, there is formed a gap which constitutes a flow passagewhich is closed by the inner peripheral surface of said shaft hole and alow pressure side surface of said annular groove in a state where saidouter peripheral ring is fitted in a normal direction, and which isopened to allow a fluid to be sealed to leak from the high pressure sideto the low pressure side in a state where said outer peripheral ring isfitted in a reverse direction.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, in the outer peripheral ring, the abutment joint portion isconstructed as mentioned above, and hence, in the state where the outerperipheral ring is fitted in the normal direction, a sealing function isexhibited, whereas in the state where the outer peripheral ring isfitted in the reverse direction, there is formed the flow passagethrough which the fluid to be sealed leaks from the high pressure sideto the low pressure side.

Accordingly, in cases where the outer peripheral ring is fitted in thereverse direction, an amount of leakage of fluid to be sealed increases,and hence, by measuring the amount of leakage, a confirmation can bemade as to whether the outer peripheral ring is fitted in the normaldirection.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thetwelfth reference example of the present disclosure will be explainedmore specifically while referring to FIG. 83 through FIG. 90. Here, notethat the basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts are denoted bythe same reference numerals and characters, and the explanation thereofis omitted as the case may be.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this reference example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O rings, but as such there can be adopted otherseal ring such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to the twelfth referenceexample of the present disclosure will be explained in further detailwhile referring in particular to FIG. 83 through FIG. 86. An abutmentjoint portion 2150 is formed on the outer peripheral ring 2000 at oneplace in a circumferential direction thereof. In addition, the outerperipheral ring 2000 is formed on its outer peripheral surface with aconcave portion 2220 for introducing fluid.

Here, note that the outer peripheral ring 2000 according to thisreference example is constructed such that the abutment joint portion2150 and the concave portion 2220 as mentioned above are formed on anannular member of which the cross section is rectangular. However, thisis only an explanation of the shape thereof, but does not necessarilymean that an annular member of a rectangular cross section is used as amaterial, and processing to form the abutment joint portion 2150 and theconcave portion 2220 is applied to this material. Of course, after anannular member of a rectangular cross section has been molded or formed,the abutment joint portion 2150 and the concave portion 2220 can also beobtained by means of cutting work. However, for example, after moldingor forming a member which has the abutment joint portion 2150 inadvance, the concave portion 2220 may be obtained by means of cuttingwork. In this manner, the method of production thereof is not limited inparticular.

The abutment joint portion 2150 has an engagement convex portion 2151which is formed at one outer peripheral surface side of a cut portionand at a low pressure side surface side, and an engagement concaveportion 2152 which is formed at the other outer peripheral surface sideand at the low pressure side surface side, and into which thisengagement convex portion 2151 is engaged. In addition, in thisreference example, the engagement convex portion 2151 and the engagementconcave portion 2152 are each constructed into a rectangularparallelepiped shape. Strictly speaking, however, an outer peripheralsurface and an inner peripheral surface thereof are curved surfaces whenviewed in an axial direction (i.e., surfaces concentric with the outerperipheral surface and the inner peripheral surface of the outerperipheral ring 2000), and the other surfaces thereof are flat or planesurfaces. Here, note that the “high pressure side” referred to herein isa high pressure side (H) in the case where the outer peripheral ring2000 is fitted in a proper direction (in a normal direction), as will bedescribed later, and the “low pressure side” is a low pressure side (L)in the case where the outer peripheral ring 2000 is fitted in the properdirection (in the normal direction).

In this reference example, too, the concave portion 2220 is formed overthe entire periphery of the outer peripheral ring 2000 except for thevicinity of the abutment joint portion 2150. The concave portion 2220 isthe same as explained in the above-mentioned embodiment, and so, thedetailed explanation thereof is omitted.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis reference example will be explained, while referring in particularto FIG. 87 and FIG. 88. FIG. 87 shows an unloaded (or low load) state inwhich the engine is stopped, and there does not exist a differentialpressure (or there exists substantially no differential pressure)between right-hand side region of the sealing device 1000 and left-handside region of the sealing device 1000. FIG. 88 shows a state in whichthe engine is operated, and fluid pressure in the right-hand side regionof the sealing device 1000 has become higher in comparison with that inthe left-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in the annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portion 2220 (i.e., a low pressure side convexportion 2210 and a portion of the outer peripheral ring 2000 in thevicinity of the abutment joint portion 2150 in which the concave portion2220 is not formed) maintain a state in which they are in contact withthe inner peripheral surface of the shaft hole in the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed to thelow pressure side (L) by means of the fluid pressure from the highpressure side (H), so that it becomes a state of being in intimatecontact with the side wall surface of the annular groove 4100 at the lowpressure side (L), as shown in FIG. 88. Here, note that it is needlessto say that the outer peripheral ring 2000 maintains the state of beingin contact (sliding) with the inner peripheral surface of the shaft holein the housing 5000. In addition, with respect to the inner peripheralring 3100, too, it also becomes a state of being in intimate contactwith the side wall surface of the annular groove 4100 at the lowpressure side (L).

<Advantages of the Sealing Device According to this Reference Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, too, by adopting the construction as mentioned above as theabutment joint portion 2150, similar to the case of the above-mentionedeleventh reference example, a confirmation as to whether the outerperipheral ring 2000 has been fitted in the normal direction or in thereverse direction can be made in a simple manner. This will be explainedbelow with reference to FIG. 86, FIG. 89 and FIG. 90. FIG. 89 is aperspective view looking obliquely at the vicinity of the abutment jointportion 2150 in the case of the outer peripheral ring 2000 being fittedin the normal direction, and FIG. 90 is a perspective view lookingobliquely at the vicinity of the abutment joint portion 2150 in the caseof the outer peripheral ring 2000 being fitted in the reverse direction.Here, note that in FIG. 89 and FIG. 90, a far or back side is the highpressure side (H), and a near or front side is the low pressure side(L).

As described above, in the abutment joint portion 2150 according to thisreference example, an engagement convex portion 2151 is formed at oneouter peripheral surface side of a cut portion and at a low pressureside surface side, and an engagement concave portion 2152, into whichthis engagement convex portion 2151 is engaged, is formed at the otherouter peripheral surface side and at the low pressure side surface side.Here, in a state where the engagement convex portion 2151 has beenfitted into the engagement concave portion 2152, a side wall surface2151 a in the engagement convex portion 2151 directed toward the highpressure side (H) and a side wall surface 2152 a in the engagementconcave portion 2152 directed toward the low pressure side (L) are inintimate contact with each other for sliding movement relative to eachother, and an inner peripheral surface 2151 b in the engagement convexportion 2151 and an outer peripheral surface 2152 b in the engagementconcave portion 2152 are in intimate contact with each other for slidingmovement relative to each other. By means of such two seal portions, asealing function is exhibited even with respect to any of the axialdirection and the radial direction.

In addition, in the abutment joint portion 2150, there is formed a gapbetween an end face 2151 c of a portion of the outer peripheral ring atone side of the cut portion except for the engagement convex portion2151, and an end face 2152 c of a portion of the outer peripheral ringat the other side except for the engagement concave portion 2152. Here,note that the longer the peripheral length of the outer peripheral ring2000 is made due to thermal expansion and contraction, the narrowerbecomes this gap, whereas the shorter the peripheral length of the outerperipheral ring 2000, the wider becomes this gap.

In cases where the outer peripheral ring 2000 is fitted in the normaldirection, this gap does not form a flow passage through which the fluidto be sealed leaks from the high pressure side (H) to the low pressureside (L), but in contrast to this, in cases where the outer peripheralring 2000 is fitted in the reverse direction, this gap forms a flowpassage through which the fluid to be sealed leaks from the highpressure side (H) to the low pressure side (L). That is, as shown inFIG. 89, in cases where the outer peripheral ring 2000 is fitted in thenormal direction, the flow passage formed by the gap is blocked orclosed by the inner peripheral surface of the shaft hole in the housing5000 (refer to an arrow A), and the flow passage formed by the gap isblocked or closed by the side wall surface of the annular groove 4100 atthe low pressure side (refer to an arrow B). Accordingly, in cases wherethe outer peripheral ring 2000 is fitted in the normal direction, thefluid to be sealed does not leak to the low pressure side (L). Incontrast to this, however, as shown in FIG. 90, in cases where the outerperipheral ring 2000 is fitted in the reverse direction, there is formeda flow passage (refer to an arrow C) through which the fluid to besealed leaks from the high pressure side (H) to the low pressure side(L).

Accordingly, by measuring an amount of leakage of fluid in a state wheredifferential pressure has been generated, it becomes possible to simplymake a confirmation as to whether the outer peripheral ring 2000 hasbeen fitted in the normal direction or in the reverse direction.

<Modification of the Twelfth Reference Example>

A modification of the twelfth reference example of the presentdisclosure is shown in FIG. 91. In this modification, a modified form ofthe abutment joint portion of the outer peripheral ring is shown in theconstruction shown in the above-mentioned twelfth reference example. Theother construction and operation of this modification are the same asthose in the above-mentioned twelfth reference example, and hence, thesame component parts as those of the above-mentioned sixteenth practicalexample are denoted by the same reference numerals and characters, andthe explanation thereof is omitted.

In an outer peripheral ring 2000 according to this modification, too, anabutment joint portion 2150 is formed on the outer peripheral ring 2000at one place in a circumferential direction thereof. In addition, theouter peripheral ring 2000 is formed on its outer peripheral surfacewith a concave portion 2220 for introducing fluid.

Then, in the abutment joint portion 2150 according to this modification,too, similar to the case of the above-mentioned twelfth referenceexample, an engagement convex portion 2155 is formed at one outerperipheral surface side of a cut portion and at a low pressure sidesurface side, and an engagement concave portion 2156, into which thisengagement convex portion 2155 is fitted, is formed at the other outerperipheral surface side and at a low pressure side surface side. Here,in the above-mentioned twelfth reference example, the engagement convexportion 2151 and the engagement concave portion 2152 are eachconstructed into a rectangular parallelepiped shape, but in contrast tothis, the engagement convex portion 2155 and the engagement concaveportion 2156 according to this modification are each constructed into atriangular prism shape. The other construction with respect to theconcave portion 2220 and the feature that the outer peripheral ring 2000together with the inner peripheral ring 3100 is fitted into the annulargroove 4100 are the same as those in the above-mentioned twelfthreference example.

In this modification, in a state where the engagement convex portion2151 has been fitted into the engagement concave portion 2156, an innerperipheral side inclined surface 2155 a in the engagement convex portion2151 and an outer peripheral side inclined surface 2156 a in theengagement concave portion 2156 are in intimate contact with each otherfor sliding movement relative to each other. These inclined surface 2155a and inclined surface 2156 a are each inclined with respect to theaxial direction, and also inclined with respect to the radial direction.Accordingly, due to the intimate contact between the inclined surface2155 a and the inclined surface 2156 a for sliding movement relative toeach other, a sealing function is exhibited even with respect to any ofthe axial direction and the radial direction.

In addition, in the abutment joint portion 2150 according to thismodification, too, similar to the case of the above-mentioned twelfthreference example, there is formed a gap between an end face 2155 c of aportion of the outer peripheral ring at one side of the cut portionexcept for the engagement convex portion 2155, and an end face 2156 c ofa portion of the outer peripheral ring at the other side except for theengagement concave portion 2156. Similar to the case of theabove-mentioned twelfth reference example, in cases where the outerperipheral ring 2000 is fitted in the normal direction, this gap doesnot form a flow passage through which the fluid to be sealed leaks fromthe high pressure side (H) to the low pressure side (L). In contrast tothis, in cases where the outer peripheral ring 2000 is fitted in thereverse direction, this gap forms a flow passage through which the fluidto be sealed leaks from the high pressure side (H) to the low pressureside (L). This mechanism is the same as in the case of theabove-mentioned twelfth reference example, so the explanation thereof isomitted.

According to the construction as mentioned above, in this modification,too, the same operational effects as in the case of the above-mentionedtwelfth reference example can be obtained.

(Others)

The gap between the end face 2151 c and the end face 2152 c shown in theabove-mentioned twelfth reference example and the gap between the endface 2155 c and the end face 2156 c shown in the modification of thetwelfth reference example become narrower or wider according to theperipheral length of the outer peripheral ring 2000. In cases wherethese gaps are lost, even if the outer peripheral ring 2000 is fitted inthe reverse direction, there will be formed no flow passage throughwhich the fluid to be sealed leaks from the high pressure side (H) tothe low pressure side (L). In addition, when the gaps become small in astate where a part of the outer peripheral side of the inner peripheralring 3100 has entered these gaps, there will be a fear that the part maybe pinched and damaged. From these reasons, it is desirable for theabove-mentioned gaps to be always formed. Accordingly, in the case ofthe above-mentioned twelfth reference example, it is preferable that thelength in the circumferential direction of the engagement convex portion2151 be set longer than the length in the circumferential direction ofthe engagement concave portion 2152. If the setting is made in thismanner, even in cases where a tip end of the engagement convex portion2151 abuts against an end face in the circumferential direction of theengagement concave portion 2152, a gap can be formed without failbetween the end face 2151 c and the end face 2152 c. In addition,similarly, in the modification of the twelfth reference example, too, ifthe length in the circumferential direction of the engagement convexportion 2155 is set longer than the length in the circumferentialdirection of the engagement concave portion 2156, the same effect willbe able to be obtained.

Thirteenth Reference Example Summary

A sealing device according to a thirteenth reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side; wherein anabutment joint portion is formed on said outer peripheral ring at oneplace in a circumferential direction thereof; wherein said abutmentjoint portion has: a first engagement convex portion formed at the lowpressure side and a first engagement concave portion formed at the highpressure side, on an outer peripheral side at one side thereof of a cutportion; and a second engagement concave portion formed at the lowpressure side into which said first engagement convex portion isengaged, and a second engagement convex portion formed at the highpressure side which is engaged into said first engagement concaveportion, on the outer peripheral side at the other side thereof of thecut portion; and wherein between an inner peripheral surface and a sidewall surface at the low pressure side in said second engagement convexportion, there is formed a fitting direction detection concave portionwhich forms a part of a flow passage through which fluid to be sealedleaks from the high pressure side to the low pressure side, in caseswhere said outer peripheral ring is fitted in a reverse direction.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, between an inner peripheral surface and a side wall surface atthe low pressure side in said second engagement convex portion, there isformed a fitting direction detection concave portion which forms a partof a flow passage through which fluid to be sealed leaks from the highpressure side to the low pressure side, in cases where said outerperipheral ring is fitted in a reverse direction. Accordingly, in caseswhere the outer peripheral ring is fitted in the reverse direction, anamount of leakage of fluid to be sealed increases, and hence, bymeasuring the amount of leakage, a confirmation can be made as towhether the outer peripheral ring is fitted in a normal direction.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thethirteenth reference example of the present disclosure will be explainedmore specifically while referring to FIG. 92 through FIG. 101. Here,note that the basic construction of this example is the same as that ofthe above-mentioned embodiment, individual reference examples andindividual practical examples, and hence, the same component parts aredenoted by the same reference numerals and characters, and theexplanation thereof is omitted as the case may be.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this reference example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O ring, but as such there can be adopted otherseal rings such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this thirteenth referenceexample of the present disclosure will be explained in further detailwhile referring in particular to FIG. 92 through FIG. 97. An abutmentjoint portion 2100 is formed on the outer peripheral ring 2000 at oneplace in a circumferential direction thereof. In addition, the outerperipheral ring 2000 is formed on its outer peripheral surface with aconcave portion 2220 for introducing fluid.

Here, note that the outer peripheral ring 2000 according to thisreference example is constructed such that the abutment joint portion2100 and the concave portion 2220 as mentioned above are formed on anannular member of which the cross section is rectangular. However, thisis only an explanation of the shape thereof, but does not necessarilymean that an annular member of a rectangular cross section is used as amaterial, and processing to form the abutment joint portion 2100 and theconcave portion 2220 is applied to this material. Of course, after anannular member of a rectangular cross section has been molded or formed,the abutment joint portion 2100 and the concave portion 2220 can also beobtained by means of cutting work. However, for example, after moldingor forming a member which has the abutment joint portion 2100 inadvance, the concave portion 2220 may be obtained by means of cuttingwork. In this manner, the method of production thereof is not limited inparticular.

Hereinafter, the abutment joint portion 2100 will be described in moredetail with particular reference to FIG. 95 through FIG. 97. FIG. 95 isa perspective view showing the vicinity of the abutment joint portion2100, and FIG. 96 is a perspective view showing one side of a cutportion in the abutment joint portion 2100, and FIG. 97 is a perspectiveview showing the other side of the cut portion in the abutment jointportion 2100.

The abutment joint portion 2100 adopts a so-called special step cutwhich is formed by being cut in a stepwise shape even when seen from anyof an outer peripheral surface side and opposite side wall surface sidesthereof. Here, note that in the case of a special step cut, there is acharacteristic of maintaining stable sealing performance even if theperipheral length of the outer peripheral ring 2000 is changed due tothermal expansion and contraction.

The abutment joint portion 2100 has a first engagement convex portion2111 formed at the low pressure side and a first engagement concaveportion 2121 formed at the high pressure side, on an outer peripheralside at one side thereof of the cut portion. In addition, the abutmentjoint portion 2100 also has a second engagement concave portion 2122formed at the low pressure side into which the first engagement convexportion 2111 is engaged, and a second engagement convex portion 2112formed at the high pressure side which is engaged into the firstengagement concave portion 2121, on the outer peripheral side at theother side thereof of the cut portion.

Here, note that the “high pressure side” referred to herein is a highpressure side (H) in the case where the outer peripheral ring 2000 isfitted in a proper direction (in a normal direction), as will bedescribed later, and the “low pressure side” is a low pressure side (L)in the case where the outer peripheral ring 2000 is fitted in the properdirection (in the normal direction).

Here, in a state where the first engagement convex portion 2111 and thesecond engagement concave portion 2122 as well as the second engagementconvex portion 2112 and the first engagement concave portion 2121 are inengagement with each other, respectively, a side wall surface 2111 adirected to the high pressure side of the first engagement convexportion 2111 and a side wall surface 2122 a directed to the low pressureside of the second engagement concave portion 2122, an inner peripheralsurface 2111 b of the first engagement convex portion 2111 and an outerperipheral surface 2122 b of the second engagement concave portion 2122,a side wall surface 2112 a directed to the low pressure side of thesecond engagement convex portion 2112 and a side wall surface 2121 adirected to the high pressure side of the first engagement concaveportion 2121, as well as an inner peripheral surface 2112 b of thesecond engagement convex portion 2112 and an outer peripheral surface2121 b of the first engagement concave portion 2121, are in contact witheach other for sliding movement relative to each other, respectively.According to such a construction, a sealing function is exhibited evenwith respect to any of the axial direction and the radial direction,without regard to the peripheral length of the outer peripheral ring2000.

Then, in the outer peripheral ring 2000 according to this referenceexample, in cases where the outer peripheral ring 2000 is fitted in thereverse direction, a fitting direction detection concave portion 2112 d,which forms a part of the flow passage through which the fluid to besealed leaks from the high pressure side to the low pressure side, isformed between the inner peripheral surface 2112 b and the side wallsurface 2112 a at the low pressure side in the second engagement convexportion 2112.

In this reference example, too, the concave portion 2220 is formed overthe entire periphery of the outer peripheral ring 2000 except for thevicinity of the abutment joint portion 2100. The concave portion 2220 isthe same as explained in the above-mentioned embodiment, and so, thedetailed explanation thereof is omitted.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis reference example will be explained, while referring in particularto FIG. 98 and FIG. 99. FIG. 98 shows an unloaded (or low load) state inwhich the engine is stopped, and there does not exist a differentialpressure (or there exists substantially no differential pressure)between right-hand side region of the sealing device 1000 and left-handside region of the sealing device 1000. FIG. 99 shows a state in whichthe engine is operated, and fluid pressure in the right-hand side regionof the sealing device 1000 has become higher in comparison with that inthe left-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in the annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, those portionsof the outer peripheral surface of the outer peripheral ring 2000 whichexclude the concave portion 2220 (i.e., a low pressure side convexportion 2210 and a portion of the outer peripheral ring 2000 in thevicinity of the abutment joint portion 2100 in which the concave portion2220 is not formed) maintain a state in which they are in contact withthe inner peripheral surface of the shaft hole in the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed to thelow pressure side (L) by means of the fluid pressure from the highpressure side (H), so that it becomes a state of being in intimatecontact with the side wall surface of the annular groove 4100 at the lowpressure side (L), as shown in FIG. 99. Here, note that it is needlessto say that the outer peripheral ring 2000 maintains the state of beingin contact (sliding) with the inner peripheral surface of the shaft holein the housing 5000. In addition, with respect to the inner peripheralring 3100, too, it also becomes a state of being in intimate contactwith the side wall surface of the annular groove 4100 at the lowpressure side (L).

<Advantages of the Sealing Device According to this Reference Example>

According to the sealing device 1000 and the sealing structure providedwith this sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in the case ofthis reference example, too, by adopting the construction as mentionedabove as the abutment joint portion 2100, similar to the case of theabove-mentioned eleventh and twelfth reference examples, a confirmationas to whether the outer peripheral ring 2000 has been fitted in thenormal direction or in the reverse direction can be made in a simplemanner. This will be explained below with reference to FIG. 100 and FIG.101. FIG. 100 is a perspective view looking obliquely at the vicinity ofthe abutment joint portion 2100 in the case of the outer peripheral ring2000 being fitted in the normal direction, and FIG. 101 is a perspectiveview looking obliquely at the vicinity of the abutment joint portion2100 in the case of the outer peripheral ring 2000 being fitted in thereverse direction. Here, note that for the sake of convenience ofexplanation, in FIG. 100, one side of the cut portion in the abutmentjoint portion 2100 is indicated by a solid line, and the other side isindicated by a broken line. In FIG. 101, the other side of the cutportion in the abutment joint portion 2100 is indicated by a solid line,and the one side is indicated by a broken line. In addition, in FIG. 100and FIG. 101, a near or front side is the high pressure side (H), and afar or back side is the low pressure side (L). Further, in FIG. 100 andFIG. 101, a broken line X indicates the position of a boundary linebetween the side wall surface at the low pressure side (L) in theannular groove 4100 and an outer peripheral surface of a shaft 4000.

In a state where the first engagement convex portion 2111 and the secondengagement concave portion 2122 as well as the second engagement convexportion 2112 and the first engagement concave portion 2121 are inengagement with each other, respectively, a gap SX is formed in theabutment joint portion 2100 between an end face 2131 of the outerperipheral ring at one side inner peripheral side of the cut portion,and an end face 2132 of the outer peripheral ring at the other sideinner peripheral side. In addition, in a state where the firstengagement convex portion 2111 and the second engagement concave portion2122 as well as the second engagement convex portion 2112 and the firstengagement concave portion 2121 are in engagement with each other,respectively, a gap SY is also formed in the abutment joint portion 2100between a tip end face 2112 c of the second engagement convex portion2112, and an end face 2121 c in the circumferential direction of thefirst engagement concave portion 2121. Moreover, in a state where thefirst engagement convex portion 2111 and the second engagement concaveportion 2122 as well as the second engagement convex portion 2112 andthe first engagement concave portion 2121 are in engagement with eachother, respectively, a gap SZ is also formed in the abutment jointportion 2100 between a tip end face 2111 c of the first engagementconvex portion 2111, and an end face 2122 c in the circumferentialdirection of the second engagement concave portion 2122.

As shown in FIG. 100, in cases where the outer peripheral ring 2000 isfitted in the normal direction, a flow passage is formed in a directionfrom the high pressure side (H) toward the low pressure side (L) bymeans of the above-mentioned gap SX (refer to an arrow A in thisfigure). However, similar to the case of a general special step cut,this gap SX is closed by the side wall surface at the low pressure side(L) of the annular groove 4100. Accordingly, there is formed no flowpassage through which the fluid to be sealed leaks from the highpressure side (H) to the low pressure side (L). Here, note that in thisreference example, the fitting direction detection concave portion 2112d is formed on the second engagement convex portion 2112, so that a flowpassage is formed which passes through the fitting direction detectionconcave portion 2112 d from the above-mentioned gap SY (refer to anarrow B in this figure). However, this flow passage, being onlyconnected with the above-mentioned gap SX, does not form a leak passage.

In contrast to this, in cases where the outer peripheral ring 2000 isfitted in the reverse direction, as shown in FIG. 101, theabove-mentioned gap SX, the fitting direction detection concave portion2112 d, and the gap SY will become a state of being connected with oneanother. For that reason, the fluid to be sealed flowing in thedirection of an arrow A passes through the fitting direction detectionconcave portion 2112 d, and flows into the gap SY (refer to an arrow Cin this figure). In this manner, in cases where the outer peripheralring 2000 is fitted in the reverse direction, there is formed a flowpassage through which the fluid to be sealed leaks from the highpressure side (H) to the low pressure side (L).

Accordingly, by measuring an amount of leakage of fluid in a state wheredifferential pressure has been generated, it becomes possible to simplymake a confirmation as to whether the outer peripheral ring 200 has beenfitted in the normal direction or in the reverse direction.

<Modification of the Thirteenth Reference Example>

A modification of the thirteenth reference example of the presentdisclosure is shown in FIG. 102. In this modification, a modified formof the abutment joint portion of the outer peripheral ring is shown inthe construction shown in the above-mentioned thirteenth referenceexample. The other construction and operation of this modification arethe same as those in the above-mentioned thirteenth reference example,and hence, the same component parts are denoted by the same referencenumerals and characters, and the explanation thereof is omitted.

In an outer peripheral ring 2000 according to this modification, too, anabutment joint portion 2100 is formed on the outer peripheral ring 2000at one place in a circumferential direction thereof. Then, the basicconstruction of the abutment joint portion 2100 in the outer peripheralring 2000 according to this modification is the same as that of theabove-mentioned thirteenth reference example. However, in the case ofthis modification, in the abutment joint portion 2100, the end face 2132at the other side inner peripheral side of the cut portion is formedinto a stepped surface. That is, the end face 2132 is composed of thestepped surface which has a low pressure side end face 2132 a and a highpressure side end face 2132 b protruded in the circumferential directionmore than the low pressure side end face 2132 a. The other constructionin the abutment joint portion 2100, the construction with respect to theconcave portion 2220, and the feature that the outer peripheral ring2000 together with the inner peripheral ring 3100 is fitted into theannular groove 4100 are the same as those in the above-mentionedthirteenth reference example.

In this modification, the high pressure side end face 2132 b protrudesin the circumferential direction, so the distance from this highpressure side end face 2132 b to the tip end face 2112 c of the secondengagement convex portion 2112 becomes short. For this reason, even ifthe end face 2131 at one side inner peripheral side of the cut portionand the high pressure side end face 2132 b at the other side innerperipheral side are in intimate contact with each other, there will beformed the gap SY as explained in the above-mentioned thirteenthreference example. In addition, because the end face 2132 is composed ofthe stepped surface, even if the end face 2131 at one side innerperipheral side of the cut portion and the high pressure side end face2132 b at the other side inner peripheral side are in intimate contactwith each other, a gap is formed, within the gap SX explained in theabove-mentioned thirteenth reference example, between the end face 2131of the outer peripheral ring at one side inner peripheral side of thecut portion, and the low pressure side end face 2132 a of the outerperipheral ring at the other side inner peripheral side. Accordingly, incases where the outer peripheral ring 2000 is fitted in the reversedirection, even if the end face 2131 at one side inner peripheral sideof the cut portion and the high pressure side end face 2132 b at theother side inner peripheral side are in intimate contact with eachother, a flow passage is formed through which the fluid to be sealedleaks from the high pressure side (H) to the low pressure side (L).

Accordingly, by measuring an amount of leakage of fluid in a state wheredifferential pressure has been generated, it becomes possible to make aconfirmation as to whether the outer peripheral ring 2000 has beenfitted in the normal direction or in the reverse direction, in a morereliable manner.

Fourteenth Reference Example Summary

A sealing device according to a fourteenth reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side; and whereina fitting engagement portion is formed on said outer peripheral ring andis constructed in such a manner that in cases where said outerperipheral ring is fitted in a normal direction, said fitting engagementportion is in fitting engagement with a fitted engagement portion formedin said annular groove so that said outer peripheral ring is fitted in acorrect posture, whereas in cases where said outer peripheral ring isfitted in a reverse direction, said fitting engagement portion is not infitting engagement with said fitted engagement portion so that saidouter peripheral ring is not fitted in the correct posture.

In addition, a sealing structure according to the fourteenth referenceexample of the present disclosure, which is provided with: a shaft and ahousing that rotate relative to each other; and a sealing device that isfitted into an annular groove formed in an outer periphery of said shaftso as to seal an annular gap between said shaft and said housing,thereby to hold a fluid pressure in a region to be sealed which isconstructed such that the fluid pressure therein changes; wherein saidsealing device comprises: an outer peripheral ring made of resin that isin intimate contact with a side wall surface of said annular groove at alow pressure side thereof, and slides with respect to an innerperipheral surface of a shaft hole in said housing through which saidshaft is inserted; and an inner peripheral ring made of a rubber-likeelastic body that is in intimate contact with an inner peripheralsurface of said outer peripheral ring and a groove bottom surface ofsaid annular groove, respectively, thereby to push said outer peripheralring toward an outer peripheral surface side thereof; said outerperipheral ring is formed on its outer peripheral surface with a concaveportion which extends from an end of a high pressure side to a positionwhich does not arrive at an end of a low pressure side, so as tointroduce fluid thereinto from the high pressure side; said annulargroove is formed with a fitted engagement portion, and said outerperipheral ring is formed with a fitting engagement portion which is infitting engagement with said fitted engagement portion; in cases wheresaid outer peripheral ring is fitted in a normal direction, said fittingengagement portion is in fitting engagement with said fitted engagementportion so that said outer peripheral ring is fitted in a correctposture; and in cases where said outer peripheral ring is fitted in areverse direction, said fitting engagement portion is not in fittingengagement with said fitted engagement portion so that said outerperipheral ring is not fitted in the correct posture.

According to the sealing device and the sealing structure according tothis reference example, the following advantages are achieved incomparison with the sealing device and the sealing structure explainedin the above-mentioned embodiment. That is, in this reference example,in cases where the outer peripheral ring is fitted in the normaldirection, the fitting engagement portion is in fitting engagement withthe fitted engagement portion so that the outer peripheral ring isfitted in the correct posture. However, in cases where the outerperipheral ring is fitted in the reverse direction, the fittingengagement portion is not in fitting engagement with the fittedengagement portion so that the outer peripheral ring is not fitted inthe correct posture. As a result, it is possible to suppress the outerperipheral ring from being fitted in the reverse direction.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thefourteenth reference example of the present disclosure will be explainedmore specifically while referring to FIG. 103 and FIG. 104. FIG. 103 isa part of a view seen from an outer peripheral surface side, showing astate where the sealing device according to the fourteenth referenceexample of the present disclosure is mounted or fitted in an annulargroove, and FIG. 104 is a cross sectional view along a line AA in FIG.103.

Here, note that the characteristic construction of the sealing deviceand the sealing structure according to this reference example can beapplied to the above-mentioned embodiment, the first through fourthpractical examples and the first through fourth and ninth referenceexamples. Here, an explanation will be made by taking an example of acase where it is applied to the first reference example. Here, note thatthe basic construction thereof is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts as those of theabove-mentioned embodiment and examples are denoted by the samereference numerals and characters, and the explanation thereof isomitted as the case may be.

As explained in the above-mentioned eleventh reference example, in thesealing devices 1000 according to the above-mentioned embodiment,individual reference examples and individual practical examples, it isnecessary to prevent the outer peripheral ring 2000 from being fitted inthe reverse direction. In the above-mentioned eleventh throughthirteenth reference examples, there have been shown cases where theconstruction of the outer peripheral ring 2000 is devised so as toconfirm whether the outer peripheral ring 2000 has been fitted in thenormal direction or in the reverse direction by measuring an amount ofleakage of fluid in a state where differential pressure has beengenerated.

In contrast to this, in this reference example, there is shown a casewhere the construction of an outer peripheral ring 2000, etc., isdevised in such a manner that the outer peripheral ring 2000 can not bemounted or fitted in the reverse direction due to its structure. Here,note that the basic construction, the operational effect and so on ofthis example are the same as explained in the above-mentioned firstreference example, and so, the detailed explanation thereof is omitted.

In the outer peripheral ring 2000 according to this reference example, aconcave portion 2520 as a fitting engagement portion is formed on a sidewall surface thereof at a side opposite to a side at which a lowpressure side convex portion 2210 is formed. In other words, the concaveportion 2520 is formed on the side wall surface which becomes a highpressure side (H) at the time of the generation of differentialpressure. Then, in an annular groove 4130, a convex portion 4131 as afitted engagement portion is formed on a side wall surface thereof whichbecomes the high pressure side (H) at the time of the generation ofdifferential pressure.

With the construction as mentioned above, at the time of fitting theouter peripheral ring 2000 into the annular groove 4130, it is possibleto mount or fit the outer peripheral ring 2000 in a proper or correctposture by mounting the concave portion 2520 so as to bring it intofitting engagement with the convex portion 4131. Here, even if the outerperipheral ring 2000 is tried to be mounted in the reverse direction,the convex portion 4131 becomes obstructive, so that the outerperipheral ring 2000 can not be mounted in its correct posture.Accordingly, it is possible to prevent the outer peripheral ring 2000from being mounted in the reverse direction by mistake. In addition, inthis reference example, a locking (rotation stop) effect is alsoexhibited by means of the fitting engagement of the concave portion 2520and the convex portion 4131, so that it is possible to suppress theouter peripheral ring 2000 from rotating with respect to a shaft 4000 ina more reliable manner.

Here, note that the number required for the concave portion 2520 and theconvex portion 4131 is not limited in particular, and one (single) ormore may be good.

Fifteenth Reference Example

A summary of description of this fifteenth reference example is the sameas that of the above-mentioned fourteenth reference example, so theexplanation thereof is omitted.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thefifteenth reference example of the present disclosure will be explainedmore specifically while referring to FIG. 105 through FIG. 108. FIG. 105is a part of a view seen from an outer peripheral surface side, showinga state where the sealing device according to the fifteenth referenceexample of the present disclosure is mounted or fitted in an annulargroove, and FIG. 106 is a cross sectional view along a line BB in FIG.105.

Here, note that the characteristic construction of the sealing deviceand the sealing structure according to this reference example can beapplied to the above-mentioned embodiment, the first through fourthpractical examples and the first through ninth reference examples. Here,an explanation will be made by taking an example of a case where it isapplied to the first reference example. Here, note that the basicconstruction of this example is the same as that of the above-mentionedembodiment, individual reference examples and individual practicalexamples, and hence, the same component parts as those of theabove-mentioned embodiment and examples are denoted by the samereference numerals and characters, and the explanation thereof isomitted as the case may be.

In this reference example, too, similar to the case of theabove-mentioned fourteenth reference example, there is shown a casewhere the construction of an outer peripheral ring 2000, etc., isdevised in such a manner that the outer peripheral ring 2000 can not bemounted or fitted in the reverse direction due to its structure. Here,note that the basic construction, the operational effect and so on ofthis example are the same as explained in the above-mentioned firstreference example, and so, the detailed explanation thereof is omitted.

In the above-mentioned fourteenth reference example, there has beenshown a construction in the case where the concave portion is formed inthe side wall surface of the outer peripheral ring, and the convexportion is formed on the side wall surface of the annular groove, but inthis reference example, there is shown a construction in the case wherea convex portion is formed on a side wall surface of an outer peripheralring, and a concave portion is formed in a side wall surface of anannular groove.

In an outer peripheral ring 2000 according to this reference example, aconvex portion 2510 as a fitting engagement portion is formed on a sidewall surface thereof at a side opposite to a side at which a lowpressure side convex portion 2210 is formed. In other words, the convexportion 2510 is formed on the side wall surface which becomes a highpressure side (H) at the time of the generation of differentialpressure. Then, in an annular groove 4140, a concave portion 4141 as afitted engagement portion is formed in a side wall surface thereof whichbecomes the high pressure side (H) at the time of the generation ofdifferential pressure. Here, note that in the illustrated example, it isconstructed such that the thickness of the convex portion 2510 becomesthe same as the thickness of a main body portion of the outer peripheralring 2000. In addition, it is also constructed such that the depth ofthe concave portion 4141 becomes the same as the depth of the annulargroove 4140.

With the construction as mentioned above, at the time of fitting theouter peripheral ring 2000 into the annular groove 4140, it is possibleto mount or fit the outer peripheral ring 2000 in a proper or correctposture by mounting the convex portion 2510 so as to bring it intofitting engagement with the concave portion 4141. Here, even if theouter peripheral ring 2000 is tried to be mounted in the reversedirection, the convex portion 2510 becomes obstructive, so that theouter peripheral ring 2000 can not be mounted in its correct posture.Accordingly, it is possible to prevent the outer peripheral ring 2000from being mounted in the reverse direction by mistake. In addition, inthis reference example, too, a locking (rotation stop) effect is alsoexhibited by means of the fitting engagement of the convex portion 2510and the concave portion 4141.

Here, note that the number required for the convex portion 2510 and theconcave portion 4141 is not limited in particular, and one (single) ormore may be good.

FIG. 107 shows a modification of the example shown in FIG. 106. Here,note that FIG. 107 corresponds to a cross section along a line BB inFIG. 105. An outer peripheral ring 2000 in this illustrated example isthe same construction as the outer peripheral ring 2000 shown in FIG.106.

Then, in the example shown in FIG. 107, too, in an annular groove 4150,a concave portion 4151 as a fitted engagement portion is formed in aside wall surface thereof which becomes the high pressure side (H) atthe time of the generation of differential pressure. Unlike the case ofthe example shown in FIG. 106, it is constructed such that the depth ofthis concave portion 4151 becomes shallower than the depth of theannular groove 4150, and is set to a depth equal to about the thicknessof the outer peripheral ring 2000. In this illustrated example, too, thesame effects as in the case of the example shown in FIG. 106 can beobtained. In addition, in the case of this example shown in FIG. 107,there is an effect of suppressing the outer peripheral ring 2000 frominclining or tilting in a clockwise direction in this figure.

FIG. 108 also shows a modification of the example shown in FIG. 106.Here, note that FIG. 108 corresponds to a cross section along the lineBB in FIG. 105.

In the case of an outer peripheral ring 2000 in this illustratedexample, a convex portion 2511 is constructed so as to protrude only inthe vicinity of an outer peripheral surface side, and the thickness ofthe convex portion 2511 is constructed to be thinner than the thicknessof a main body portion of the outer peripheral ring 2000. In addition,the depth of a concave portion 4161 in this illustrated example is alsoconstructed to be shallower than the depth of an annular groove 4160,and is set to a depth equal to about the thickness of the convex portion2511. In this illustrated example, too, the same effects as in the caseof the example shown in FIG. 107 can be obtained. Here, note that in thecase of the example shown in FIG. 108, there may be adopted aconstruction in which the convex portion 2511 and the concave portion4161 are formed so as to extend over the entire peripheries of the outerperipheral ring and the annular groove, respectively. In other words, itmay be constructed such that the convex portion 2511 becomes an annularconvex portion and the concave portion 4161 becomes an annular concaveportion, instead of being partially formed in singularity or inplurality in a circumferential direction. In this case, although alocking (rotation stop) effect is not exhibited, there is an advantagethat processing, in particular for forming the concave portion 4161,becomes easy.

Sixteenth Reference Example

A summary of description of this sixteenth reference example is the sameas that of the above-mentioned fourteenth reference example, so theexplanation thereof is omitted.

Specific Example

Hereinafter, a sealing device and a sealing structure according to thesixteenth reference example of the present disclosure will be explainedwhile referring to FIG. 109 and FIG. 110. FIG. 109 is a part of a viewseen from an outer peripheral surface side, showing a state where thesealing device according to the sixteenth reference example of thepresent disclosure is mounted or fitted in an annular groove, and FIG.110 is a cross sectional view along a line CC in FIG. 109.

Here, note that the characteristic construction of the sealing deviceand the sealing structure according to this reference example can beapplied to the above-mentioned embodiment, the first through fourthpractical examples and the first through four and ninth referenceexamples. Here, an explanation will be made by taking an example of acase where it is applied to the first reference example. Here, note thatthe basic construction thereof is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts as those of theabove-mentioned embodiment and examples are denoted by the samereference numerals and characters, and the explanation thereof isomitted as the case may be.

In this reference example, too, similar to the case of theabove-mentioned fourteenth reference example, there is shown a casewhere the construction of an outer peripheral ring 2000, etc., isdevised in such a manner that the outer peripheral ring 2000 can not bemounted or fitted in the reverse direction due to its structure. Here,note that the basic construction, the operational effect and so on ofthis example are the same as explained in the above-mentioned firstreference example, and so, the detailed explanation thereof is omitted.

In the above-mentioned fourteenth reference example, there has beenshown the construction in the case where the concave portion is formedin the side wall surface of the outer peripheral ring, and the convexportion is formed on the side wall surface of the annular groove, but inthis reference example, there is shown a construction in the case wherea convex portion is formed on an inner peripheral surface of an outerperipheral ring at a high pressure side, and a concave portion is formedin a groove bottom surface of an annular groove at a high pressure side.

In an outer peripheral ring 2000 according to this reference example, aconvex portion 2314 as a fitting engagement portion is formed on aninner peripheral surface thereof near a side opposite to a side at whicha low pressure side convex portion 2210 is formed. In other words, theconvex portion 2314 is formed on the inner peripheral surface at a sidewhich becomes a high pressure side (H) at the time of the generation ofdifferential pressure. Then, in a groove bottom surface of an annulargroove 4170, a concave portion 4171 as a fitted engagement portion isformed at a side which becomes the high pressure side (H) at the time ofthe generation of differential pressure.

With the construction as mentioned above, at the time of fitting theouter peripheral ring 2000 into the annular groove 4170, it is possibleto mount or fit the outer peripheral ring 2000 in a proper or correctposture by mounting the convex portion 2314 so as to bring it intofitting engagement with the concave portion 4171. Here, even if theouter peripheral ring 2000 is tried to be mounted in the reversedirection, the convex portion 2314 becomes obstructive, so that theouter peripheral ring 2000 can not be mounted in its correct posture.Accordingly, it is possible to prevent the outer peripheral ring 2000from being mounted in the reverse direction by mistake. In addition, inthis reference example, too, a locking (rotation stop) effect is alsoexhibited by means of the fitting engagement of the convex portion 2314and the concave portion 4171.

Here, note that the number required for the convex portion 2314 and theconcave portion 4171 is not limited in particular, and one (single) ormore may be good.

In addition, in the case of this reference example, there may be adopteda construction in which the convex portion 2314 and the concave portion4171 are formed over the entire peripheries of the outer peripheral ringand the annular groove, respectively. In other words, it may beconstructed such that the convex portion 2314 becomes an annular convexportion and the concave portion 4171 becomes an annular concave portion,instead of being partially formed in singularity or in plurality in acircumferential direction. In this case, although a locking (rotationstop) effect is not exhibited, there is an advantage that processing, inparticular for forming the concave portion 4171, becomes easy.

Seventeenth Reference Example

A summary of description of this seventeenth reference example is thesame as that of the above-mentioned fourteenth reference example, so theexplanation thereof is omitted.

Specific Example

Hereinafter, a sealing device and a sealing structure according to theseventeenth reference example of the present disclosure will beexplained while referring to FIG. 111 and FIG. 112. FIG. 111 is a partof a view seen from an outer peripheral surface side, showing a statewhere the sealing device according to the seventeenth reference exampleof the present disclosure is mounted or fitted in an annular groove, andFIG. 112 is a cross sectional view along a line DD in FIG. 111.

Here, note that the characteristic construction of the sealing deviceand the sealing structure according to this reference example can beapplied to the above-mentioned embodiment, the first through fourthpractical examples and the first through eighth and tenth referenceexamples. Here, an explanation will be made by taking an example of acase where it is applied to the first reference example. Here, note thatthe basic construction of this example is the same as that of theabove-mentioned embodiment, individual reference examples and individualpractical examples, and hence, the same component parts as those of theabove-mentioned embodiment and examples are denoted by the samereference numerals and characters, and the explanation thereof isomitted as the case may be.

In this reference example, too, similar to the case of theabove-mentioned fourteenth reference example, there is shown a casewhere the construction of an outer peripheral ring 2000, etc., isdevised in such a manner that the outer peripheral ring 2000 can not bemounted or fitted in the reverse direction due to its structure. Here,note that the basic construction, the operational effect and so on ofthis example are the same as explained in the above-mentioned firstreference example, and so, the detailed explanation thereof is omitted.

In the above-mentioned sixteenth reference example, there has been showna construction in the case where the convex portion is formed on theinner peripheral surface of the outer peripheral ring at the highpressure side, and the concave portion is formed in the groove bottomsurface of the annular groove at the high pressure side. In thisreference example, however, there is shown a construction in the casewhere a convex portion is formed on an inner peripheral surface of anouter peripheral ring at a low pressure side, and a concave portion isformed in a groove bottom surface of an annular groove at a low pressureside.

In an outer peripheral ring 2000 according to this reference example, aconvex portion 2315 as a fitting engagement portion is formed on aninner peripheral surface thereof near a side at which a low pressureside convex portion 2210 is formed. In other words, the convex portion2315 is formed on the inner peripheral surface at a side which becomes alow pressure side (L) at the time of the generation of differentialpressure. Then, in a groove bottom surface of an annular groove 4180, aconcave portion 4181 as a fitted engagement portion is formed at a sidewhich becomes the low pressure side (L) at the time of the generation ofdifferential pressure.

With the construction as mentioned above, at the time of fitting theouter peripheral ring 2000 into the annular groove 4180, it is possibleto mount or fit the outer peripheral ring 2000 in a proper or correctposture by mounting the convex portion 2315 so as to bring it intofitting engagement with the concave portion 4181. Here, even if theouter peripheral ring 2000 is tried to be mounted in the reversedirection, the convex portion 2315 becomes obstructive, so that theouter peripheral ring 2000 can not be mounted in its correct posture.Accordingly, it is possible to prevent the outer peripheral ring 2000from being mounted in the reverse direction by mistake. In addition, inthis reference example, too, a locking (rotation stop) effect is alsoexhibited by means of the fitting engagement of the convex portion 2315and the concave portion 4181.

Here, note that the number required for the convex portion 2315 and theconcave portion 4181 is not limited in particular, and one (single) ormore may be good.

In addition, in the case of this reference example, there may be adopteda construction in which the convex portion 2315 and the concave portion4181 are formed over the entire peripheries of the outer peripheral ringand the annular groove, respectively. In other words, it may beconstructed such that the convex portion 2315 becomes an annular convexportion and the concave portion 4181 becomes an annular concave portion,instead of being partially formed in singularity or in plurality in acircumferential direction. In this case, although a locking (rotationstop) effect is not exhibited, there is an advantage that processing, inparticular for forming the concave portion 4181, becomes easy.

Eighteenth Reference Example Summary

A sealing device according to an eighteenth reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surface andover an entire periphery thereof with a concave portion which extendsfrom an end of a high pressure side to a position which does not arriveat an end of a low pressure side, so as to introduce fluid thereintofrom the high pressure side.

In addition, a sealing structure according to the eighteenth referenceexample of the present disclosure, which is provided with: a shaft and ahousing that rotate relative to each other; and a sealing device that isfitted into an annular groove formed in an outer periphery of said shaftso as to seal an annular gap between said shaft and said housing,thereby to hold a fluid pressure in a region to be sealed which isconstructed such that the fluid pressure therein changes; wherein saidsealing device comprises: an outer peripheral ring made of resin that isin intimate contact with a side wall surface of said annular groove at alow pressure side thereof, and slides with respect to an innerperipheral surface of a shaft hole in said housing through which saidshaft is inserted; and an inner peripheral ring made of a rubber-likeelastic body that is in intimate contact with an inner peripheralsurface of said outer peripheral ring and a groove bottom surface ofsaid annular groove, respectively, thereby to push said outer peripheralring toward an outer peripheral surface side thereof; said outerperipheral ring is formed on its outer peripheral surface and over anentire periphery thereof with a concave portion which extends from anend of a high pressure side to a position which does not arrive at anend of a low pressure side, so as to introduce fluid thereinto from thehigh pressure side; and a protrusion portion is formed on the innerperipheral surface of said shaft hole in a position opposing to saidconcave portion in the case where said outer peripheral ring is fittedin a normal direction, and is constructed to protrude toward an innerperipheral surface side up to a position which does not reach a bottomsurface of said concave portion, so that when said shaft is fitted intothe shaft hole with said outer peripheral ring being fitted in saidannular groove in a reverse direction, an outer peripheral convexportion remaining on the outer peripheral surface side of said outerperipheral ring without the formation of said concave portion is caughtin so that said shaft can not be fitted in a regular position.

According to the sealing device according to this reference example,there can be obtained the same operational effects as in the sealingdevice explained in the above-mentioned embodiment. In addition,according to the sealing structure according to this reference example,the following advantages are achieved in comparison with the sealingstructure explained in the above-mentioned embodiment. That is, in thisreference example, the protrusion portion is formed on the innerperipheral surface of the shaft hole in the housing, and hence, in caseswhere the outer peripheral ring has been fitted in the reverse directionby mistake, the shaft can not be mounted in the regular position. As aresult, it is possible to suppress the outer peripheral ring from beingfitted in the reverse direction.

Specific Example

Hereinafter, a sealing device and a sealing structure according to theeighteenth reference example of the present disclosure will be explainedmore specifically while referring to FIG. 113 through FIG. 118. Here,note that the basic construction of this example is the same as that ofthe above-mentioned embodiment, individual reference examples andindividual practical examples, and hence, the same component parts asthose of the above-mentioned embodiment and examples are denoted by thesame reference numerals and characters, and the explanation thereof isomitted as the case may be.

A sealing device 1000 according to this reference example is composed ofan outer peripheral ring 2000 made of resin, and an inner peripheralring 3100 made of a rubber-like elastic body. The inner peripheral ring3100 according to this reference example is a so-called O ring having acircular cross sectional shape. However, the inner peripheral ring 3100is not limited to the O ring, but as such there can be adopted otherseal rings such as a rectangular or polygonal ring, etc.

It is constructed such that in a state where the outer peripheral ring2000 and the inner peripheral ring 3100 are combined or assembledtogether, a peripheral length of an outer peripheral surface of theouter peripheral ring 2000 becomes longer than a peripheral length of aninner peripheral surface of a shaft hole in a housing 5000, as explainedin the above-mentioned embodiment. Here, note that for the outerperipheral ring 2000 as a single or separate member, the peripherallength of the outer peripheral surface thereof is made shorter than theperipheral length of the inner peripheral surface of the shaft hole inthe housing 5000, as explained in the above-mentioned embodiment.

<Outer Peripheral Ring>

The outer peripheral ring 2000 according to this reference example ofthe present disclosure will be explained in further detail whilereferring in particular to FIG. 113 through FIG. 115. The outerperipheral ring 2000 is formed on its outer peripheral surface and anentire periphery thereof with a concave portion 2220 for introducingfluid. In other words, the outer peripheral ring 2000 is formed at ahigh pressure side in its outer peripheral surface with an annularconcave portion 2220.

Here, note that the outer peripheral ring 2000 according to thisreference example is constructed such that the concave portion 2220 asmentioned above is formed on an annular member of which the crosssection is rectangular. However, this is only an explanation of theshape thereof, but does not necessarily mean that an annular member of arectangular cross section is used as a material, and processing to formthe concave portion 2220 is applied to this material. Of course, afteran annular member of a rectangular cross section has been molded orformed, the concave portion 2220 can also be obtained by means ofcutting work. However, the outer peripheral ring 2000 having the concaveportion 2220 may be molded or formed. In this manner, the method ofproduction thereof is not limited in particular.

Moreover, the concave portion 2220 is formed to extend from an end ofthe high pressure side to a position which does not reach an end of thelow pressure side. In addition, more specifically, this concave portion2220 is formed so as to extend to the vicinity of the low pressure sideend. Here, note that a bottom surface of the concave portion 2220 iscomposed of a surface which is concentric with an inner peripheralsurface of the outer peripheral ring 2000.

Here, note that the shallower the depth of the concave portion 2220, thehigher becomes the rigidity of that portion of the outer peripheral ring2000 in which a low pressure side convex portion 2210 is formed. On theother hand, the low pressure side convex portion 2210 is worn out due tothe relative sliding movement thereof, so the depth of the concaveportion 2220 becomes shallower as the time elapses. For that reason,when the depth of the concave portion 2220 becomes too much shallow, itwill become impossible to introduce fluid therein. Accordingly, it isdesirable to set an initial depth of the concave portion 2220 by takinginto consideration both the above-mentioned rigidity and the maintenanceof introduction of fluid even if the wear progresses with the lapse oftime. For example, in cases where the thickness of the outer peripheralring 2000 is 1.7 mm, it is preferable to set the depth of the concaveportions 2220 to be equal to or more than about 0.1 mm and equal to orless than about 0.3 mm. In addition, the narrower the width of the lowpressure side convex portion 2210, the more the torque can be reduced,but if the width is made too much narrow, sealing efficiency anddurability will become low. Accordingly, it is desirable to narrow thewidth concerned as much as possible according to service conditions,etc., to such an extent that sealing efficiency and durability can bemaintained. Here, note that for example, in cases where the entirelength of the width (width in the axial direction) of the outerperipheral ring 2000 is 1.9 mm, it is preferable to set the width of thelow pressure side convex portion 2210 to be equal to or more than about0.3 mm and equal to or less than about 0.7 mm.

<Mechanism at the Time of Using the Sealing Device>

A mechanism at the time of using the sealing device 1000 according tothis reference example will be explained, while referring in particularto FIG. 116 and FIG. 117. FIG. 116 shows an unloaded (or low load) statein which the engine is stopped, and there does not exist a differentialpressure (or there exists substantially no differential pressure)between right-hand side region of the sealing device 1000 and left-handside region of the sealing device 1000. FIG. 117 shows a state in whichthe engine is operated, and fluid pressure in the right-hand side regionof the sealing device 1000 has become higher in comparison with that inthe left-hand side region of the sealing device 1000.

In a state where the sealing device 1000 is fitted in the annular groove4100, the inner peripheral ring 3100 made of a rubber-like elastic bodyis in intimate contact with the inner peripheral surface of the outerperipheral ring 2000 and a groove bottom surface of the annular groove4100, respectively. Then, the inner peripheral ring 3100 exhibits afunction of pushing the outer peripheral ring 2000 toward its outerperipheral surface side due to the elastic repulsion thereof.

Accordingly, even if the engine is in an unloaded state, that portion ofthe outer peripheral surface of the outer peripheral ring 2000 whichexcludes the concave portion 2220 (i.e., the low pressure side convexportion 2210) maintains a state in which they are in contact with theinner peripheral surface of the shaft hole in the housing 5000.

Then, in a state in which the engine is started to generate adifferential pressure, the outer peripheral ring 2000 is pushed to thelow pressure side (L) by means of the fluid pressure from the highpressure side (H), so that it becomes a state of being in intimatecontact with the side wall surface of the annular groove 4100 at the lowpressure side (L), as shown in FIG. 117. Here, note that it is needlessto say that the outer peripheral ring 2000 maintains the state of beingin contact (sliding) with the inner peripheral surface of the shaft holein the housing 5000. In addition, with respect to the inner peripheralring 3100, too, it also becomes a state of being in intimate contactwith the side wall surface of the annular groove 4100 at the lowpressure side (L).

<Advantages of the Sealing Device and the Sealing Structure According tothis Reference Example>

According to the sealing device 1000 according to this referenceexample, too, there can be obtained the same operational effects as inthe sealing device explained in the above-mentioned embodiment.

Here, as explained in the above-mentioned eleventh reference example, inthe sealing device 1000, it is necessary to prevent the outer peripheralring 2000 from being mounted or fitted in the reverse direction.Accordingly, in this reference example, the outer peripheral ring 2000is prevented from being mounted or fitted in the reverse direction, bydevising the structure of the inner peripheral surface of the shaft holein the housing 5000. In the following, this feature will be described.

In this reference example, as shown in FIG. 116 and FIG. 117, there isadopted a construction in which a protrusion portion is formed on theinner peripheral surface of the shaft hole in the housing 5000 in aposition opposing to the concave portion 2220 in the case where theouter peripheral ring 2000 is mounted or fitted in the normal direction.More specifically, the inner peripheral surface of the shaft hole isconstructed of a surface with a step which is composed of a largediameter portion 5110 and a small diameter portion 5120 of which theinside diameter is smaller than that of the large diameter portion 5110.The large diameter portion 5110 corresponds to a part in which the lowpressure side convex portion 2210 in the outer peripheral ring 2000slides. In addition, the small diameter portion 5120 is formed in aposition which is in opposition to the concave portion 2220 in the casewhere the outer peripheral ring 2000 is mounted in the normal direction,and the small diameter portion 5120 corresponds to the above-mentionedprotrusion portion. This small diameter portion 5120 is constructed soas to protrude toward an inner peripheral surface side up to a positionwhich does not reach the bottom surface of the concave portion 2220.With the construction as mentioned above, if a shaft 4000 is fitted intothe shaft hole in a direction of an arrow X in FIG. 118, with the outerperipheral ring 2000 being fitted in the annular groove 4100 in thereverse direction, the low pressure side convex portion 2210 will becaught in or obstructed by the small diameter portion 5120 (morespecifically, the stepped surface 5130 of the large diameter portion5110 and the small diameter portion 5120). For this reason, it isimpossible to mount the shaft 4000 in a regular or proper position. As aresult, it is possible to know the outer peripheral ring 2000 fromhaving been fitted into the annular groove 4100 in the reverse directionby mistake. From the above, it is possible to prevent the outerperipheral ring 2000 from being fitted in the reverse direction.

Here, note that in this reference example, there has been shown a casewhere the inner peripheral surface of the shaft hole is constructed ofthe stepped surface, as the protrusion portion formed on the innerperipheral surface of the shaft hole in the housing 5000. However, theconstruction of the protrusion portion is not limited to such astructure. In brief, it should be such that in cases where the shaft4000 is fitted into the shaft hole with the outer peripheral ring 2000being fitted in the annular groove 4100 in the reverse direction, thelow pressure side convex portion 2210 is caught in the protrusionportion so that the shaft 4000 can not be fitted in the regularposition. Accordingly, this protrusion portion can also be constructedof a single protrusion or a plurality of protrusions, partially formedin a circumferential direction. In addition, the protrusion portion maybe constructed of a protrusion partially formed with respect to theaxial direction. In this case, the protrusion may be formed insingularity or in plurality partially in the circumferential direction,or may be an annular protrusion.

In addition, in order to improve the mountability (fitting ability oreasiness) of the outer peripheral ring 2000, an abutment joint portionsuch as a straight cut, a bias cut, etc., may be formed at one place inthe outer peripheral ring 2000 in the circumferential direction.

Nineteenth Reference Example Summary

A sealing device according to a nineteenth reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side.

Then, said inner peripheral ring is an annular member of which the crosssection cut by a plane including an axis thereof is a V shape, and whichforms an annular seal portion at one place with respect to the groovebottom surface of said annular groove, and annular seal portions at twoplaces with respect to the inner peripheral surface of said outerperipheral ring.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, the inner peripheral ring and the outer peripheral ring are incontact with each other in a plurality of locations. For that reason,even in a state where the fluid pressure does not act, or in a statewhere the fluid pressure does not substantially act, the outerperipheral ring is made to be held in a stable manner. In addition, in astate where the fluid pressure is high and differential pressure ishigh, the inner peripheral ring will be in a state of being deformedunder compression in the axial direction, as well as being moved to thelow pressure side. As a result of this, the inner peripheral ring pushesthe outer peripheral ring toward its outer peripheral surface side, byacting on a low pressure side portion of the inner peripheral surface inthe outer peripheral ring. Accordingly, it is possible to stabilize theintimate contact of the outer peripheral ring with respect to the innerperipheral surface of the shaft hole to a further extent.

Specific Example

Hereinafter, an inner peripheral ring according to the nineteenthreference example of the present disclosure will be explained whilereferring to FIG. 119 and FIG. 120. Here, note that the construction andoperation of this example other than the inner peripheral ring are thesame as those in the above-mentioned embodiment, and hence, the samecomponent parts as those of the above-mentioned embodiment are denotedby the same reference numerals and characters, and the explanationthereof is omitted.

An inner peripheral ring 3110 according to this reference example iscomposed of a rubber-like elastic body such as acrylic rubber (ACM),fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc. Inaddition, the inner peripheral ring 3110 according to this referenceexample is an annular member of which the cross section cut by a planeincluding an axis thereof is a V shape. Here, note that the “axis” is acentral axis of the inner peripheral ring 3110, and coincides with acentral axis of a shaft 4000 in a state where the inner peripheral ring3110 has been fitted into an annular groove 4100. Moreover, the innerperipheral ring 3110 is a symmetrical shape with respect to a centerplane in an axial direction thereof.

The inner peripheral ring 3110 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in an outer peripheral ring 2000 and a groove bottom surface ofthe annular groove 4100, respectively. Then, the inner peripheral ring3110 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, the inner peripheral ring 3110 serves to form anannular seal portion 3113 at one place with respect to the groove bottomsurface of the annular groove 4100, and annular seal portions 3111, 3112at two places with respect to the inner peripheral surface of the outerperipheral ring 2000.

Here, in an unloaded condition, there is no differential pressurebetween left-hand side and right-hand side regions, as shown in FIG.119, so that the inner peripheral ring 3110 can be in a state of beingaway from a side wall surface at the left side in this figure in theannular groove 4100. Then, in a state in which the engine is started togenerate a differential pressure, the inner peripheral ring 3110 ispushed by means of the fluid pressure from the high pressure side (H),so that it becomes a state of being in intimate contact with the sidewall surface of the annular groove 4100 at the low pressure side (L), asshown in FIG. 120. At this time, the inner peripheral ring 3110 will bein a state of being inserted or clamped between the fluid pressure atthe high pressure side (H) and the side wall surface at the low pressureside (L) in the annular groove 4100, so that it is deformed in such amanner as to narrow the space or distance between the annular sealportions 3111, 3112 at two places on its outer peripheral side.

As described above, in the sealing device according to this referenceexample, the inner peripheral ring 3110 takes a symmetrical shape withrespect to the center plane in the axial direction, so it is notnecessary to take into consideration the direction of mounting orfitting at the time when the inner peripheral ring 3110 is mounted orfitted into the annular groove 4100. In addition, the inner peripheralring 3110 and the outer peripheral ring 2000 are in contact with eachother in a plurality of locations, as a result of which even in a statewhere the fluid pressure does not act, or in a state where the fluidpressure does not substantially act, the outer peripheral ring 2000 ismade to be held in a stable manner. Moreover, in a state where the fluidpressure is high and so the differential pressure is high, the innerperipheral ring 3110 will be in a state of being deformed undercompression in the axial direction, as well as being moved to the lowpressure side (L). As a result of this, the inner peripheral ring 3110pushes the outer peripheral ring 2000 toward its outer peripheralsurface side, by acting on the portion at the low pressure side (L) ofthe inner peripheral surface in the outer peripheral ring 2000.Accordingly, it is possible to stabilize the intimate contact of theouter peripheral ring 2000 with respect to the inner peripheral surfaceof the shaft hole to a further extent.

Here, note that the inner peripheral ring 3110 explained in thisreference example can also be applied, among the above-mentionedindividual reference examples and individual practical examples, tovarious kinds of reference examples and practical examples in which thestatement “the inner peripheral ring 3100 is not limited to the O ring,but as such there can be adopted other seal rings such as a rectangularor polygonal ring, etc.” is described.

Twentieth Reference Example Summary

A sealing device according to a twentieth reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side.

Then, said inner peripheral ring is an annular member of which the crosssection cut by a plane including an axis thereof is an X shape, andwhich forms annular seal portions at two places with respect to thegroove bottom surface of said annular groove, and annular seal portionsat two places with respect to the inner peripheral surface of said outerperipheral ring.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, by forming the inner peripheral ring in such a manner that thecross section thereof cut by a plane including an axis thereof takes anX shape, it is possible to make it difficult for a twist to occur at thetime when the inner peripheral ring is fitted into the annular groove.In addition, the inner peripheral ring is in contact, at two places,with each of the outer peripheral ring and the groove bottom surface, sothat it is possible to reduce a deviation in the distribution of thepushing pressure or force by the inner peripheral ring with respect tothe inner peripheral surface of the outer peripheral ring. Accordingly,even in a state where the fluid pressure does not act, or in a statewhere the fluid pressure does not substantially act, or even in a statewhere the fluid pressure is high and differential pressure is high, theouter peripheral ring is held in a stable manner.

Specific Example

Hereinafter, an inner peripheral ring according to the twentiethreference example of the present disclosure will be explained whilereferring to FIG. 121 and FIG. 122. Here, note that the construction andoperation of this example other than the inner peripheral ring are thesame as those in the above-mentioned embodiment, and hence, the samecomponent parts as those of the above-mentioned embodiment are denotedby the same reference numerals and characters, and the explanationthereof is omitted.

An inner peripheral ring 3120 according to this reference example iscomposed of a rubber-like elastic body such as acrylic rubber (ACM),fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc. Inaddition, the inner peripheral ring 3120 according to this referenceexample is an annular member of which the cross section cut by a planeincluding an axis thereof is an X shape. Here, note that the “axis” is acentral axis of the inner peripheral ring 3120, and coincides with acentral axis of a shaft 4000 in a state where the inner peripheral ring3120 has been fitted into an annular groove 4100. Moreover, the innerperipheral ring 3120 is a symmetrical shape with respect to a centerplane in an axial direction thereof.

The inner peripheral ring 3120 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in an outer peripheral ring 2000 and a groove bottom surface ofthe annular groove 4100, respectively. Then, the inner peripheral ring3120 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, the inner peripheral ring 3120 serves to formannular seal portions 3123, 3124 at two places with respect to thegroove bottom surface of the annular groove 4100, and annular sealportions 3121, 3122 at two places with respect to the inner peripheralsurface of the outer peripheral ring 2000.

Here, in an unloaded condition, there is no differential pressurebetween left-hand side and right-hand side regions, as shown in FIG.121, so that the inner peripheral ring 3120 can be in a state of beingaway from a side wall surface at the left side in this figure in theannular groove 4100. Then, in a state in which the engine is started togenerate a differential pressure, the inner peripheral ring 3120 ispushed by means of the fluid pressure from the high pressure side (H),so that it becomes a state of being in intimate contact with the sidewall surface of the annular groove 4100 at the low pressure side (L), asshown in FIG. 122. At this time, the inner peripheral ring 3120 will bein a state of being inserted or clamped between the fluid pressure atthe high pressure side (H) and the side wall surface at the low pressureside (L) in the annular groove 4100, so that it is deformed in such amanner as to narrow the spaces or distances between the annular sealportions 3121, 3122 at two places on its outer peripheral side, andbetween the annular seal portions 3123, 3124 at two places on its innerperipheral side, respectively.

As described above, in the sealing device according to this referenceexample, by forming the inner peripheral ring 3120 in such a manner thatthe cross section thereof cut by the plane including the axis thereoftakes the X shape, it is possible to make it difficult for a twist tooccur at the time when the inner peripheral ring 3120 is fitted into theannular groove 4100. In addition, the inner peripheral ring 3120 takes asymmetrical shape with respect to the center plane in the axialdirection, so it is not necessary to take into consideration thedirection of mounting or fitting at the time when the inner peripheralring 3120 is mounted or fitted into the annular groove 4100. Moreover,the inner peripheral ring 3120 is in contact, at two places, with eachof the inner peripheral surface of the outer peripheral ring 2000 andthe groove bottom surface of the annular groove 4100, so that it ispossible to reduce a deviation in the distribution of the pushingpressure or force by the inner peripheral ring 3120 with respect to theinner peripheral surface of the outer peripheral ring 2000. Accordingly,even in a state where the fluid pressure does not act, or in a statewhere the fluid pressure does not substantially act, or even in a statewhere the fluid pressure is high and differential pressure is high, theouter peripheral ring 2000 is held in a stable manner.

Here, note that the inner peripheral ring 3120 explained in thisreference example can also be applied, among the above-mentionedindividual reference examples and individual practical examples, tovarious kinds of reference examples and practical examples in which thestatement “the inner peripheral ring 3100 is not limited to the O ring,but as such there can be adopted other seal rings such as a rectangularor polygonal ring, etc.” is described.

Twenty-First Reference Example Summary

A sealing device according to a twenty-first reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side.

Then, said inner peripheral ring is an annular member of which the crosssection cut by a plane including an axis thereof is a y shape, and whichforms annular seal portions at two places with respect to the groovebottom surface of said annular groove, and an annular seal portion atone place with respect to the inner peripheral surface of said outerperipheral ring; and said inner peripheral ring is disposed in such amanner that a surface thereof facing the high pressure side becomes onlya tapered surface which increases in diameter from the high pressureside toward the low pressure side.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, by constructing the inner peripheral ring in the manner asmentioned above, in a state where the fluid pressure is high anddifferential pressure is high, a force directing to an inner peripheralsurface side acts on the inner peripheral ring. For that reason, it ispossible to suppress the pushing force of the inner peripheral ring withrespect to the outer peripheral ring to push it toward its outerperipheral surface side. Accordingly, an increase in pressure toward theouter peripheral surface side by means of the outer peripheral ringaccompanying the increase in the fluid pressure can be suppressed, thusmaking it possible to suppress sliding torque to a low level.

Specific Example

Hereinafter, an inner peripheral ring according to the twenty-firstreference example of the present disclosure will be explained whilereferring to FIG. 123 and FIG. 124. Here, note that the construction andoperation of this example other than the inner peripheral ring are thesame as those in the above-mentioned embodiment, and hence, the samecomponent parts as those of the above-mentioned embodiment are denotedby the same reference numerals and characters, and the explanationthereof is omitted.

An inner peripheral ring 3130 according to this reference example iscomposed of a rubber-like elastic body such as acrylic rubber (ACM),fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc. Inaddition, the inner peripheral ring 3130 according to this referenceexample is an annular member of which the cross section cut by a planeincluding an axis thereof is a y shape. Here, note that the “axis” is acentral axis of the inner peripheral ring 3130, and coincides with acentral axis of a shaft 4000 in a state where the inner peripheral ring3130 has been fitted into an annular groove 4100. Also, note that it isneedless to say that with respect to the cross section obtained bycutting the inner peripheral ring 3130 by the above-mentioned plane, across sectional shape at one side of a cut portion becomes a y-charactershape, whereas a cross sectional shape at the other side becomes a shapeof a mirror image with respect to the y character.

The inner peripheral ring 3130 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in an outer peripheral ring 2000 and a groove bottom surface ofthe annular groove 4100, respectively. Then, the inner peripheral ring3130 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, the inner peripheral ring 3130 serves to formannular seal portions 3132, 3133 at two places with respect to thegroove bottom surface of the annular groove 4100, and an annular sealportion 3131 at one place with respect to the inner peripheral surfaceof the outer peripheral ring 2000. Moreover, in this reference example,the inner peripheral ring 3130 is disposed in such a manner that a longrectilinear portion in the y character is directed to a high pressureside (H). As a result of this, a surface facing the high pressure side(H) in the inner peripheral ring 3130 becomes only a tapered surfacewhich increases in diameter from the high pressure side (H) toward a lowpressure side (L).

Here, in an unloaded condition, there is no differential pressurebetween left-hand side and right-hand side regions, as shown in FIG.123, so that the inner peripheral ring 3130 can be in a state of beingaway from a side wall surface at the left side in this figure in theannular groove 4100. Then, in a state in which the engine is started togenerate a differential pressure, the inner peripheral ring 3130 ispushed by means of the fluid pressure from the high pressure side (H),so that it becomes a state of being in intimate contact with the sidewall surface of the annular groove 4100 at the low pressure side (L), asshown in FIG. 124. At this time, the inner peripheral ring 3130 will bein a state of being inserted or clamped between the fluid pressure atthe high pressure side (H) and the side wall surface at the low pressureside (L) in the annular groove 4100, so that it is deformed in such amanner as to narrow the space or distance between the annular sealportions 3132, 3133 at two places on its inner peripheral side.

As described above, in the sealing device according to this referenceexample, the surface facing the high pressure side (H) in the innerperipheral ring 3130 becomes only the tapered surface which increases indiameter from the high pressure side (H) toward the low pressure side(L). As a result of this, in a state where the fluid pressure is highand differential pressure is high, a force directing to an innerperipheral surface side acts on the inner peripheral ring 3130. For thatreason, it is possible to suppress the pushing force of the innerperipheral ring 3130 with respect to the outer peripheral ring 2000 topush it toward its outer peripheral surface side. Accordingly, anincrease in pressure toward the outer peripheral surface side by meansof the outer peripheral ring 2000 accompanying the increase in the fluidpressure can be suppressed, thus making it possible to suppress slidingtorque to a low level.

Here, note that the inner peripheral ring 3130 explained in thisreference example can also be applied, among the above-mentionedindividual reference examples and individual practical examples, tovarious kinds of reference examples and practical examples in which thestatement “the inner peripheral ring 3100 is not limited to the O ring,but as such there can be adopted other seal rings such as a rectangularor polygonal ring, etc.” is described.

Twenty-Second Reference Example Summary

A sealing device according to a twenty-second reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side.

Then, said inner peripheral ring is an annular member of which the crosssection cut by a plane including an axis thereof is a C-character shape,and which forms an annular seal portion at one place with respect to thegroove bottom surface of said annular groove, and an annular sealportion at one place with respect to the inner peripheral surface ofsaid outer peripheral ring; and said inner peripheral ring is disposedin such a manner that an opening side in said C character is directed tothe low pressure side.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, by constructing the inner peripheral ring in the manner asmentioned above, the size of an outside diameter thereof can be setlarger and the size of an inside diameter thereof can be set smaller, ascompared with the case where an O ring is adopted as the innerperipheral ring, so that the areas of contact of the inner peripheralring with respect to the outer peripheral ring and the groove bottomsurface of the annular groove can be made wider. Accordingly, even in astate where the fluid pressure does not act, or in a state where thefluid pressure does not substantially act, the outer peripheral ring canbe made to be held in a stable manner. In addition, the inner peripheralring is hollow in its interior, and so, is easy to deform into aninterior side. For that reason, even in a state where the fluid pressureis high and differential pressure is high, the inner peripheral ringitself is deformed, thereby making it possible to suppress the pushingforce of the inner peripheral ring with respect to the outer peripheralring to push it toward its outer peripheral surface side. Accordingly,an increase in pressure toward the outer peripheral surface side bymeans of the outer peripheral ring accompanying the increase in thefluid pressure can be suppressed, thus making it possible to suppresssliding torque to a low level.

Specific Example

Hereinafter, an inner peripheral ring according to the twenty-secondreference example of the present disclosure will be explained whilereferring to FIG. 125 and FIG. 126. Here, note that the construction andoperation of this example other than the inner peripheral ring are thesame as those in the above-mentioned embodiment, and hence, the samecomponent parts as those of the above-mentioned embodiment are denotedby the same reference numerals and characters, and the explanationthereof is omitted.

An inner peripheral ring 3140 according to this reference example iscomposed of a rubber-like elastic body such as acrylic rubber (ACM),fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc. Inaddition, the inner peripheral ring 3140 according to this referenceexample is an annular member of which the cross section cut by a planeincluding an axis thereof is a C shape. Here, note that the “axis” is acentral axis of the inner peripheral ring 3140, and coincides with acentral axis of a shaft 4000 in a state where the inner peripheral ring3140 has been fitted into an annular groove 4100. Also, note that it isneedless to say that with respect to the cross section obtained bycutting the inner peripheral ring 3140 by the above-mentioned plane, across sectional shape at one side of a cut portion becomes a C-charactershape, whereas a cross sectional shape at the other side becomes a shapeof a mirror image with respect to the C character.

The inner peripheral ring 3140 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in an outer peripheral ring 2000 and a groove bottom surface ofthe annular groove 4100, respectively. Then, the inner peripheral ring3140 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, the inner peripheral ring 3140 serves to form anannular seal portion 3142 at one place with respect to the groove bottomsurface of the annular groove 4100, and an annular seal portion 3141 atone place with respect to the inner peripheral surface of the outerperipheral ring 2000. Moreover, in this reference example, the innerperipheral ring 3140 is disposed in such a manner that an opening sidein the C character is directed to a low pressure side (L).

Here, in an unloaded condition, there is no differential pressurebetween left-hand side and right-hand side regions, as shown in FIG.125, so that the inner peripheral ring 3140 can be in a state of beingaway from a side wall surface at the left side in this figure in theannular groove 4100. Then, in a state in which the engine is started togenerate a differential pressure, the inner peripheral ring 3140 ispushed by means of the fluid pressure from the high pressure side (H),so that it becomes a state of being in intimate contact with the sidewall surface of the annular groove 4100 at the low pressure side (L), asshown in FIG. 126. At this time, the inner peripheral ring 3140 will bein a state of being inserted or clamped between the fluid pressure atthe high pressure side (H) and the side wall surface at the low pressureside (L) in the annular groove 4100, so that it is deformed to becompressed in an axial direction.

As described above, in the sealing device according to this referenceexample, as the inner peripheral ring 3140, there is adopted an annularmember of which the cross section cut by a plane including an axisthereof is a C shape. With this, the size of an outside diameter of theinner peripheral ring 3140 can be set larger, and the size of an insidediameter thereof can be set smaller, as compared with the case where anO ring is adopted as the inner peripheral ring. As a result of this, theareas of contact of the inner peripheral ring 3140 with respect to theouter peripheral ring 2000 and the groove bottom surface of the annulargroove 4100 can be made wider. Accordingly, even in a state where thefluid pressure does not act, or in a state where the fluid pressure doesnot substantially act, the outer peripheral ring 2000 can be made to beheld in a stable manner.

In addition, the inner peripheral ring 3140 is hollow in its interior,and so, is easy to deform into an interior side. For that reason, evenin a state where the fluid pressure is high and differential pressure ishigh, the inner peripheral ring 3140 itself is deformed, thereby makingit possible to suppress the pushing force of the inner peripheral ring3140 with respect to the outer peripheral ring 2000 to push it towardits outer peripheral surface side. Accordingly, an increase in pressuretoward the outer peripheral surface side by means of the outerperipheral ring 2000 accompanying the increase in the fluid pressure canbe suppressed, thus making it possible to suppress sliding torque to alow level.

Here, note that the inner peripheral ring 3140 explained in thisreference example can also be applied, among the above-mentionedindividual reference examples and individual practical examples, tovarious kinds of reference examples and practical examples in which thestatement “the inner peripheral ring 3100 is not limited to the O ring,but as such there can be adopted other seal rings such as a rectangularor polygonal ring, etc.” is described.

Twenty-Third Reference Example Summary

A sealing device according to a twenty-third reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side; and whereinsaid inner peripheral ring is in intimate contact with the entire innerperipheral surface of said outer peripheral ring.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, a construction is adopted in which the inner peripheral ring isin intimate contact with the entire inner peripheral surface of theouter peripheral ring. With such a construction, it is possible tosuppress the fluid pressure from acting on the inner peripheral surfaceof the outer peripheral ring, so that sliding torque can be furthersuppressed to a low level. In addition, the entire inner peripheralsurface of the outer peripheral ring is supported by the innerperipheral ring, so that the posture of the outer peripheral ring isstabilized.

Specific Example

A sealing device according to the twenty-third reference example of thepresent disclosure will be explained, while referring to FIG. 127. FIG.127 is a schematic cross sectional view showing a high pressure state inthe sealing device according to the twenty-third reference example ofthe present disclosure. Here, note that an arrow in FIG. 127 shows howthe fluid pressure acts with respect to the outer peripheral ring 2000.

With respect to the outer peripheral ring 2000 in this referenceexample, its construction is the same as that explained in theabove-mentioned embodiment, and so, the detailed explanation thereof isomitted.

An inner peripheral ring 3150 according to this reference example iscomposed of a rubber-like elastic body such as acrylic rubber (ACM),fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc. Inaddition, the inner peripheral ring 3150 according to this referenceexample is composed of an annular member, and is formed on its innerperipheral surface side and its opposite side surface sides with annulargrooves 3151, 3152, 3153, respectively. More specifically, theconstruction is such that the annular grooves 3151, 3152, 3153 areformed at the inner peripheral surface side and the opposite sidesurface sides, respectively, of a so-called rectangular ring of whichthe cross section is rectangular. Then, the width (the length in anaxial direction) of the inner peripheral ring 3150 is designed to be thesame size as the width of the outer peripheral ring 2000.

The inner peripheral ring 3150 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in the outer peripheral ring 2000 and a groove bottom surface ofan annular groove 4100, respectively. Then, the inner peripheral ring3150 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, the inner peripheral ring 3150 is in intimatecontact with the entire inner peripheral surface of the outer peripheralring 2000.

According to the sealing device 1000 constructed as described above,because there is adopted the construction in which the inner peripheralring 3150 is in intimate contact with the entire inner peripheralsurface of the outer peripheral ring 2000, there will be obtained thefollowing effects in addition to the operational effects explained inthe above-mentioned embodiment. That is, it is possible to suppress thefluid pressure from acting on the inner peripheral surface of the outerperipheral ring 2000. Accordingly, it is possible to suppress slidingtorque to a low level to a further extent. In addition, the entire innerperipheral surface of the outer peripheral ring 2000 is supported by theinner peripheral ring 3150, so that the posture of the outer peripheralring 2000 is stabilized.

In addition, in this reference example, because the annular grooves3151, 3152 and 3153 are formed at the inner peripheral surface side andthe opposite side surface sides, respectively, of the inner peripheralring 3150, the repulsive force of the inner peripheral ring 3150 isreduced in an appropriate manner. As a result of this, a pressing loadto the outer peripheral ring 2000 is stabilized, so that a pressurepattern (i.e., surface pressure distribution) on a sealing surface canbe made uniform.

Here, note that the inner peripheral ring 3150 explained in thisreference example can also be applied, among the above-mentionedindividual reference examples and individual practical examples, tovarious kinds of reference examples and practical examples in which thestatement “the inner peripheral ring 3100 is not limited to the O ring,but as such there can be adopted other seal rings such as a rectangularor polygonal ring, etc.” is described.

Twenty-Fourth Reference Example Summary

A sealing device according to a twenty-fourth reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side; and whereinsaid inner peripheral ring is in intimate contact with the entire innerperipheral surface of said outer peripheral ring.

In addition, in a central position in a width direction at the outerperipheral surface side of said outer peripheral ring, there is formedan outer peripheral convex portion which extends in a circumferentialdirection with its outer peripheral surface being slidable with respectto the inner peripheral surface of said shaft hole; and a portion in theouter peripheral surface side of said outer peripheral ring at a higherpressure side than said outer peripheral convex portion is said concaveportion.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, a construction is adopted in which the inner peripheral ring isin intimate contact with the entire inner peripheral surface of theouter peripheral ring. With such a construction, it is possible tosuppress the fluid pressure from acting on the inner peripheral surfaceof the outer peripheral ring, so that sliding torque can be furthersuppressed to a low level. In addition, the entire inner peripheralsurface of the outer peripheral ring is supported by the innerperipheral ring, so that the posture of the outer peripheral ring isstabilized. Further, the outer peripheral ring slides with respect tothe inner peripheral surface of the shaft hole in the central positionin the width direction, so that the posture of the outer peripheral ringcan be stabilized to a further extent.

Specific Example

A sealing device according to the twenty-fourth reference example of thepresent disclosure will be explained, while referring to FIG. 128 andFIG. 129. FIG. 128 is a schematic cross sectional view showing a highpressure state in the sealing device according to the twenty-fourthreference example of the present disclosure. FIG. 129 is a partiallybroken perspective view of an outer peripheral ring according to thetwenty-fourth reference example of the present disclosure. Here, notethat an arrow in FIG. 128 shows how the fluid pressure acts with respectto the outer peripheral ring 2000.

With respect to an inner peripheral ring 3150 according to thisreference example, its construction is the same as that explained in theabove-mentioned twenty-third reference example, and so, the detailedexplanation thereof is omitted.

The outer peripheral ring 2000 according to this reference example isdifferent from the outer peripheral ring explained in theabove-mentioned embodiment, in that in a central position in a widthdirection at an outer peripheral surface side thereof, there is formedan outer peripheral convex portion 2215 which extends in acircumferential direction with its outer peripheral surface beingslidable with respect to an inner peripheral surface of a shaft hole ina housing 5000. Here, note that a portion in the outer peripheralsurface side of the outer peripheral ring 2000 at a higher pressure side(H) than the outer peripheral convex portion 2215 is a concave portion2223 for introducing fluid.

In addition, in this reference example, too, similar to theabove-mentioned twenty-third reference example, the width (the length inan axial direction) of the inner peripheral ring 3150 is designed to bethe same size as the width of the outer peripheral ring 2000.

In the sealing device 1000 as constructed in the above manner, too, thesame operational effects as in the case of the above-mentionedtwenty-third reference example can be obtained.

Here, note that in the case of this reference example, a region in theouter peripheral surface side of the outer peripheral ring 2000 in whichthe concave portion 2223 is formed is in a position deviated toward ahigh pressure side (H) from the center in the width direction.Accordingly, a force by which the outer peripheral ring 2000 is pushedtoward its inner peripheral surface side by means of the fluid pressureis reduced in comparison with the case of the outer peripheral ring 2000shown in the above-mentioned embodiment. However, in the case of thisreference example, the outer peripheral ring 2000 slides with respect tothe inner peripheral surface of the shaft hole in the housing 5000, inthe central position in the width direction, so that the posture of theouter peripheral ring 2000 can be stabilized to a further extent. Inaddition, in the case of the outer peripheral ring 2000 shown in theabove-mentioned embodiment, it is necessary to mount or fit the outerperipheral ring 2000 in such a manner that the low pressure side convexportion 2210 is disposed at the low pressure side (L). In contrast tothis, in the case of the outer peripheral ring 2000 according to thisreference example, even if it is mounted or fitted in either direction,the concave portion 2223 will exist at the high pressure side (H), andhence, this outer peripheral ring 2000 is excellent in respect ofmounting or fitting workability. Here, note that with respect to thesetting of the width size of the outer peripheral convex portion 2215,it is the same as that in the case of the low pressure side convexportion 2210 shown in the above-mentioned embodiment. Accordingly, thefeature that a sliding area between the outer peripheral ring 2000 andthe inner peripheral surface of the shaft hole in the housing 5000 issufficiently narrower than an area of intimate contact between the outerperipheral ring 2000 and the side wall surface of the annular groove4100 at the low pressure side (L) is similar to the case of theabove-mentioned embodiment.

Twenty-Fifth Reference Example

A summary of description of this twenty-fifth reference example is thesame as that of the above-mentioned twenty-fourth reference example, sothe explanation thereof is omitted.

Specific Example

A sealing device according to the twenty-fifth reference example of thepresent disclosure will be explained, while referring to FIG. 130. FIG.130 is a schematic cross sectional view showing a high pressure state inthe sealing device according to the twenty-fifth reference example ofthe present disclosure. Here, note that an arrow in FIG. 130 shows howthe fluid pressure acts with respect to the outer peripheral ring 2000.

With respect to an outer peripheral ring 2000 in this reference example,its construction is the same as that explained in the above-mentionedtwenty-fourth reference example, and so, the detailed explanationthereof is omitted.

An inner peripheral ring 3160 according to this reference example iscomposed of a rubber-like elastic body such as acrylic rubber (ACM),fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc. Inaddition, the inner peripheral ring 3160 according to this referenceexample is composed of an annular member, and is formed on its innerperipheral surface side with an annular groove 3161. More specifically,the construction is such that the annular groove 3161 is formed at theinner peripheral surface side of a so-called rectangular ring of whichthe cross section is rectangular. Then, the width (the length in anaxial direction) of the inner peripheral ring 3160 is designed to be thesame size as the width of the outer peripheral ring 2000.

The inner peripheral ring 3160 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in the outer peripheral ring 2000 and a groove bottom surface ofan annular groove 4100, respectively. Then, the inner peripheral ring3160 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, the inner peripheral ring 3160 is in intimatecontact with the entire inner peripheral surface of the outer peripheralring 2000.

According to the sealing device 1000 as constructed in the above manner,the same operational effects as in the case of the above-mentionedtwenty-fourth reference example can be obtained. Here, note that withrespect to the outer peripheral ring 2000, there can also be adopted theouter peripheral ring shown in the above-mentioned embodiment.

Here, note that the inner peripheral ring 3160 explained in thisreference example can also be applied, among the above-mentionedindividual reference examples and individual practical examples, tovarious kinds of reference examples and practical examples in which thestatement “the inner peripheral ring 3100 is not limited to the O ring,but as such there can be adopted other seal rings such as a rectangularor polygonal ring, etc.” is described.

Twenty-Sixth Reference Example

A summary of description of this twenty-sixth reference example is thesame as that of the above-mentioned twenty-fourth reference example, sothe explanation thereof is omitted.

Specific Example

A sealing device according to the twenty-sixth reference example of thepresent disclosure will be explained, while referring to FIG. 131. FIG.131 is a schematic cross sectional view showing a high pressure state inthe sealing device according to the twenty-sixth reference example ofthe present disclosure. Here, note that an arrow in FIG. 131 shows howthe fluid pressure acts with respect to an outer peripheral ring 2000.

With respect to the outer peripheral ring 2000 in this referenceexample, its construction is the same as that explained in theabove-mentioned twenty-fourth reference example, and so, the detailedexplanation thereof is omitted.

An inner peripheral ring 3170 according to this reference example iscomposed of a rubber-like elastic body such as acrylic rubber (ACM),fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc. Inaddition, the inner peripheral ring 3170 according to this referenceexample is a so-called rectangular ring of which the cross section isrectangular. Then, the width (the length in an axial direction) of theinner peripheral ring 3170 is designed to be the same size as the widthof the outer peripheral ring 2000.

The inner peripheral ring 3170 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in the outer peripheral ring 2000 and a groove bottom surface ofan annular groove 4100, respectively. Then, the inner peripheral ring3170 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, the inner peripheral ring 3170 is in intimatecontact with the entire inner peripheral surface of the outer peripheralring 2000.

According to the sealing device 1000 as constructed in the above manner,the same operational effects as in the case of the above-mentionedtwenty-fourth reference example can be obtained. Here, note that withrespect to the outer peripheral ring 2000, there can also be adopted theouter peripheral ring shown in the above-mentioned embodiment.

Here, note that the inner peripheral ring 3160 explained in thisreference example can also be applied, among the above-mentionedindividual reference examples and individual practical examples, tovarious kinds of reference examples and practical examples in which thestatement “the inner peripheral ring 3100 is not limited to the O ring,but as such there can be adopted other seal rings such as a rectangularor polygonal ring, etc.” is described.

Twenty-Seventh Reference Example Summary

A sealing device according to a twenty-seventh reference example of thepresent disclosure, which is fitted into an annular groove formed in anouter periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side; whereinsaid outer peripheral ring is formed on its inner peripheral surfaceside with an inner peripheral convex portion which extends in acircumferential direction; and wherein said inner peripheral ring isformed on its outer peripheral surface side with a groove which is inengagement with said inner peripheral convex portion.

According to the sealing device according to this reference example, thefollowing advantages are achieved in comparison with the sealing deviceexplained in the above-mentioned embodiment. That is, in this referenceexample, there is adopted a construction in which the outer peripheralring is formed on its inner peripheral surface side with the innerperipheral convex portion which extends in the circumferentialdirection, and the inner peripheral ring is formed on its outerperipheral surface side with the groove which is in engagement with thisinner peripheral convex portion. Accordingly, the position of the innerperipheral ring with respect to the outer peripheral ring is settled orfixed, so that the posture of the outer peripheral ring is stabilized.

It is preferable that said inner peripheral ring be set to a size inwhich a gap is formed between the inner peripheral ring and the sidewall surface of said annular groove at the low pressure side thereof ina state where the groove formed in the inner peripheral ring is inengagement with said inner peripheral convex portion.

With this, the inner peripheral convex portion formed on the outerperipheral ring is pushed to the low pressure side by the groove formedin the inner peripheral ring, so that a state of the outer peripheralring being in intimate contact with the side wall surface of the annulargroove at the low pressure side is maintained in a stable manner.

Specific Example

A sealing device according to the twenty-seventh reference example ofthe present disclosure will be explained, while referring to FIG. 132.FIG. 132 is a schematic cross sectional view showing a high pressurestate in the sealing device according to the twenty-seventh referenceexample of the present disclosure. Here, note that an arrow in FIG. 132shows how the fluid pressure acts with respect to a sealing device 1000.

In an outer peripheral ring 2000 according to this reference example, aninner peripheral convex portion 2316 extending in a circumferentialdirection is formed on an inner peripheral surface side thereof. Theother construction of this example is the same as the construction ofthe outer peripheral ring 2000 explained in the above-mentionedembodiment, and hence, the same component parts as those of theabove-mentioned embodiment are denoted by the same reference numeralsand characters, and the explanation thereof is omitted. Here, note thatthe inner peripheral convex portion 2316 may be formed over an entireperiphery in a circumferential direction (but excluding the vicinity ofan abutment joint portion in cases where such an abutment joint portionis formed), or may be formed in plurality at intervals in thecircumferential direction.

In addition, an inner peripheral ring 3180 according to this referenceexample is composed of a rubber-like elastic body such as acrylic rubber(ACM), fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc.Moreover, the inner peripheral ring 3180 according to this referenceexample is a so-called X ring of which the cross section is anX-character shape. Accordingly, it is constructed such that an annulargroove 3181 is formed on an outer peripheral surface side of the innerperipheral ring 3180, so that this groove 3181 is in engagement with theinner peripheral convex portion 2316 formed on the outer peripheral ring2000. Further, the inner peripheral ring 3180 is designed such that itswidth (i.e., length in the axial direction) is shorter than the width ofthe outer peripheral ring 2000, so that a gap S is formed between theinner peripheral ring 3180 and a side wall surface of the annular groove4100 at a low pressure side (L) thereof in a state where the groove 3181formed in the inner peripheral ring 3180 is in engagement with the innerperipheral convex portion 2316.

The inner peripheral ring 3180 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in the outer peripheral ring 2000 and a groove bottom surface ofthe annular groove 4100, respectively. Then, the inner peripheral ring3180 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, in a state where differential pressure has beengenerated, due to a combination of the formation of the gap S and theengagement of the groove 3181 with the inner peripheral convex portion2316, as mentioned above, the inner peripheral convex portion 2316 inthe outer peripheral ring 2000 is pushed toward the low pressure side(L) (refer to an arrow X).

According to the sealing device 1000 constructed as described above, thefollowing effects will be obtained in addition to the operationaleffects explained in the above-mentioned embodiment. That is, due to theengagement between the inner peripheral convex portion 2316 of the outerperipheral ring and the groove 3181 in the inner peripheral ring 3180,the position of the inner peripheral ring 3180 with respect to the outerperipheral ring 2000 is settled or fixed. Accordingly, the posture ofthe outer peripheral ring 2000 is made stable. In addition, as mentionedabove, in a state where differential pressure has been generated, theinner peripheral convex portion 2316 is pushed to the low pressure side(L), so that the state of the outer peripheral ring 2000 being inintimate contact with the side wall surface of the annular groove 4100at the low pressure side (L) is maintained in a stable manner.

Twenty-Eighth Reference Example

A summary of description of this twenty-eighth reference example is thesame as that of the above-mentioned twenty-seventh reference example, sothe explanation thereof is omitted.

Specific Example

A sealing device according to the twenty-eighth reference example of thepresent disclosure will be explained, while referring to FIG. 133. FIG.133 is a schematic cross sectional view showing a high pressure state inthe sealing device according to the twenty-eighth reference example ofthe present disclosure. Here, note that an arrow in FIG. 133 shows howthe fluid pressure acts with respect to a sealing device 1000.

With respect to an outer peripheral ring 2000 according to thisreference example, its construction is the same as that explained in theabove-mentioned twenty-seventh reference example, and so, the detailedexplanation thereof is omitted.

In addition, an inner peripheral ring 3190 according to this referenceexample is composed of a rubber-like elastic body such as acrylic rubber(ACM), fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc.Moreover, the inner peripheral ring 3190 according to this referenceexample has a construction in which a so-called rectangular ring havinga rectangular cross section is formed on its outer peripheral surfaceside with an annular groove 3191. Then, this groove 3191 is constructedso as to be in engagement with an inner peripheral convex portion 2316formed on the outer peripheral ring 2000. Further, the inner peripheralring 3190 is designed such that its width (i.e., length in the axialdirection) is shorter than the width of the outer peripheral ring 2000,so that a gap S is formed between the inner peripheral ring 3190 and aside wall surface of an annular groove 4100 at a low pressure side (L)thereof in a state where the groove 3191 formed in the inner peripheralring 3190 is in engagement with the inner peripheral convex portion2316.

The inner peripheral ring 3190 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in the outer peripheral ring 2000 and a groove bottom surface ofthe annular groove 4100, respectively. Then, the inner peripheral ring3190 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, in a state where differential pressure has beengenerated, due to a combination of the formation of the gap S and theengagement of the groove 3181 with the inner peripheral convex portion2316, as mentioned above, the inner peripheral convex portion 2316 inthe outer peripheral ring 2000 is pushed toward the low pressure side(L) (refer to an arrow X).

According to the sealing device 1000 as constructed in the above manner,the same operational effects as in the case of the above-mentionedtwenty-seventh reference example can be obtained.

Twenty-Ninth Reference Example

A summary of description of this twenty-ninth reference example is thesame as that of the above-mentioned twenty-seventh reference example, sothe explanation thereof is omitted.

Specific Example

A sealing device according to the twenty-ninth reference example of thepresent disclosure will be explained, while referring to FIG. 134. FIG.134 is a schematic cross sectional view showing a high pressure state inthe sealing device according to the twenty-ninth reference example ofthe present disclosure. Here, note that an arrow in FIG. 134 shows howthe fluid pressure acts with respect to a sealing device 1000.

With respect to an outer peripheral ring 2000 according to thisreference example, its construction is the same as that explained in theabove-mentioned twenty-seventh reference example, and so, the detailedexplanation thereof is omitted.

In addition, an inner peripheral ring 3200 according to this referenceexample is composed of a rubber-like elastic body such as acrylic rubber(ACM), fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc.Moreover, the inner peripheral ring 3200 according to this referenceexample has a construction in which a so-called D ring having aD-character shaped cross section is formed on its outer peripheralsurface side with an annular groove 3201. Then, this groove 3201 isconstructed so as to be in engagement with an inner peripheral convexportion 2316 formed on the outer peripheral ring 2000. Further, theinner peripheral ring 3200 is designed such that its width (i.e., lengthin the axial direction) is shorter than the width of the outerperipheral ring 2000, so that a gap S is formed between the innerperipheral ring 3200 and a side wall surface of an annular groove 4100at a low pressure side (L) thereof in a state where the groove 3201formed in the inner peripheral ring 3200 is in engagement with the innerperipheral convex portion 2316.

The inner peripheral ring 3200 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in the outer peripheral ring 2000 and a groove bottom surface ofthe annular groove 4100, respectively. Then, the inner peripheral ring3200 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, in a state where differential pressure has beengenerated, due to a combination of the formation of the gap S and theengagement of the groove 3201 with the inner peripheral convex portion2316, as mentioned above, the inner peripheral convex portion 2316 inthe outer peripheral ring 2000 is pushed toward the low pressure side(L) (refer to an arrow X).

According to the sealing device 1000 as constructed in the above manner,the same operational effects as in the case of the above-mentionedtwenty-seventh reference example can be obtained.

Thirtieth Reference Example

A summary of description of this thirtieth reference example is the sameas that of the above-mentioned twenty-seventh reference example, so theexplanation thereof is omitted.

Specific Example

A sealing device according to the thirtieth reference example of thepresent disclosure will be explained, while referring to FIG. 135. FIG.135 is a schematic cross sectional view showing a high pressure state inthe sealing device according to the thirtieth reference example of thepresent disclosure. Here, note that an arrow in FIG. 135 shows how thefluid pressure acts with respect to a sealing device 1000.

With respect to an outer peripheral ring 2000 according to thisreference example, its construction is the same as that explained in theabove-mentioned twenty-seventh reference example, and so, the detailedexplanation thereof is omitted.

In addition, an inner peripheral ring 3210 according to this referenceexample is composed of a rubber-like elastic body such as acrylic rubber(ACM), fluororubber (FKM), hydrogenated nitrile rubber (HNBR), etc.Moreover, the inner peripheral ring 3210 according to this referenceexample has a construction in which a so-called rectangular ring havinga rectangular cross section is formed on its inner and outer peripheralsurface sides with grooves, respectively. Then, a groove 3211 on theouter peripheral surface side is constructed so as to be in engagementwith an inner peripheral convex portion 2316 formed on the outerperipheral ring 2000. Further, the inner peripheral ring 3210 isdesigned such that its width (i.e., length in the axial direction) isshorter than the width of the outer peripheral ring 2000, so that a gapS is formed between the inner peripheral ring 3210 and a side wallsurface of an annular groove 4100 at a low pressure side (L) thereof ina state where the groove 3211 formed in the inner peripheral ring 3210is in engagement with the inner peripheral convex portion 2316.

The inner peripheral ring 3210 as constructed in this manner, at thetime of the use thereof, is in intimate contact with an inner peripheralsurface in the outer peripheral ring 2000 and a groove bottom surface ofthe annular groove 4100, respectively. Then, the inner peripheral ring3210 exhibits a function of pushing the outer peripheral ring 2000toward its outer peripheral surface side due to the elastic repulsionthereof. In addition, in a state where differential pressure has beengenerated, due to a combination of the formation of the gap S and theengagement of the groove 3211 with the inner peripheral convex portion2316, as mentioned above, the inner peripheral convex portion 2316 inthe outer peripheral ring 2000 is pushed toward the low pressure side(L) (refer to an arrow X).

According to the sealing device 1000 as constructed in the above manner,the same operational effects as in the case of the above-mentionedtwenty-seventh reference example can be obtained.

Thirty-First Reference Example Summary

In this reference example, reference will be made to a constructionwhich can be used in a suitable manner in cases where in theabove-mentioned embodiment, individual reference examples and individualpractical examples, a special step cut is adopted as an abutment jointportion in an outer peripheral ring.

That is, a sealing device according to the thirty-first referenceexample of the present disclosure, wherein an abutment joint portion isformed in an outer peripheral ring at one place in a circumferentialdirection thereof; said abutment joint portion, by being cut in astepwise shape even when seen from any of an outer peripheral surfaceside and opposite side wall surface sides thereof, is formed, on anouter peripheral side at one side thereof of a cut portion, with a firstengagement convex portion and a first engagement concave portion, and isalso formed, on the outer peripheral side at the other side thereof ofthe cut portion, with a second engagement concave portion into whichsaid first engagement convex portion is engaged, and a second engagementconvex portion which is engaged into said first engagement concaveportion; and a length from one end face of an inner peripheral side inthe cut portion to a tip end of the first engagement convex portion islonger than a length from the one end face of the inner peripheral sidein the cut portion to a rear end of the first engagement concaveportion, and a length from the other end face of the inner peripheralside in the cut portion to a tip end of the second engagement convexportion is longer than a length from the other end face of the innerperipheral side in the cut portion to a rear end of the secondengagement concave portion.

For this reason, even if the peripheral length of the outer peripheralring becomes longer due to its thermal expansion so that the outerperipheral ring is put into a state where the tip end of the firstengagement convex portion is in abutment against the rear end of thesecond engagement concave portion, and the tip end of the secondengagement convex portion is in abutment against the rear end of thefirst engagement concave portion, a state will be maintained in which agap is formed between the end faces of the inner peripheral side in thecut portion. Accordingly, it is possible to suppress the innerperipheral ring from being damaged by the end faces of the innerperipheral side in the cut portion being clamped or pinched with eachother.

Specific Example

The thirty-first reference example of the present disclosure is shown inFIG. 136 and FIG. 137. In this reference example, a modified form of theabutment joint portion of the outer peripheral ring is shown in theconstruction shown in each of the above-mentioned embodiment, individualreference examples and individual practical examples. The otherconstruction and operation of this modification are the same as those inthe above-mentioned embodiment, and hence, the same component parts asthose of the above-mentioned embodiment are denoted by the samereference numerals and characters, and the explanation thereof isomitted.

An abutment joint portion 2170 in an outer peripheral ring 2000according to this reference example also adopts a so-called special stepcut which is formed by being cut in a stepwise shape even when seen fromany of an outer peripheral surface side and opposite side wall surfacesides thereof, as in the case of the above-mentioned embodiment. As aresult of this, in the outer peripheral ring 2000, a first engagementconvex portion 2171 a and a first engagement concave portion 2172 a areformed at one outer peripheral side of a cut portion, and a secondengagement concave portion 2172 b into which the first engagement convexportion 2571 a is engaged, and a second engagement convex portion 2171 bwhich is engaged into the first engagement concave portion 2172 a areformed at the other outer peripheral side.

Here, note that in FIG. 136, an end portion at one side of the cutportion in the abutment joint portion 2170 is shown in a perspectiveview. In addition, in FIG. 137, there is shown a view in which thevicinity of the abutment joint portion 2170 is seen from a side surfacethereof.

In general, in the case of the special step cut, a length from one endface of an inner peripheral side (i.e., an end face of one end) in thecut portion to a tip end of a first engagement convex portion(corresponding to L1 in the figure), a length from the one end face to arear end of a first engagement concave portion (corresponding to L2 inthe figure), a length from the other end face of the inner peripheralside (i.e., an end face of the other end) in the cut portion to a tipend of a second engagement convex portion (corresponding to L1 in thefigure), and a length from the other end face to a rear end of a secondengagement concave portion (corresponding to L2 in the figure) are setto be equal to one another. Accordingly, as the peripheral length of theouter peripheral ring becomes longer due to its thermal expansion, at acertain point of time, the tip end of the first engagement convexportion comes into abutment against the rear end of the secondengagement concave portion, and the tip end of the second engagementconvex portion comes into abutment against the rear end of the firstengagement concave portion, and the inner peripheral side end faces ofthe outer peripheral ring comes into abutment against each other, at thesame time. In other words, it becomes a state where a gap hasdisappeared between the end faces of the outer peripheral ring atopposite sides of the cut portion.

Accordingly, in the abutment joint portion, the gap between the endfaces at opposite sides of the cut portion varies (i.e., becomes largeror smaller) in accordance with the thermal expansion and contraction ofthe outer peripheral ring. For that reason, in a construction in whichan inner peripheral ring made of a rubber-like elastic body is providedinside the outer peripheral ring, when the gap becomes small in a statewhere a part of an outer peripheral side of the inner peripheral ringhas entered the gap, there will be a fear that the part may be pinchedand damaged.

Accordingly, in the abutment joint portion 2170 of the outer peripheralring 2000 according to this reference example, the length L1 from theone end face of the inner peripheral side (the end face of one end) inthe cut portion to the tip end of the first engagement convex portion2171 a is set to be longer than the length L2 from the one end face ofthe inner peripheral side (the end face of the one end) in the cutportion to the rear end of the first engagement concave portion 2172 a,and the length L1 from the other end face of the inner peripheral side(the end face of the other end) in the cut portion to the tip end of thesecond engagement convex portion 2171 b is set to be longer than thelength L2 from the other end face of the inner peripheral side (the endface of the other end) in the cut portion to the rear end of the secondengagement concave portion 2172 b. Here, note that the length from theone end face of the inner peripheral side (the end face of the one end)in the cut portion to the tip end of the first engagement convex portion2171 a and the length from the other end face of the inner peripheralside (the end face of the other end) in the cut portion to the tip endof the second engagement convex portion 2171 b are each the same lengthL1. In addition, the length from the one end face of the innerperipheral side (the end face of the one end) in the cut portion to therear end of the first engagement concave portion 2172 a and the lengthfrom the other end face of the inner peripheral side (the end face ofthe other end) in the cut portion to the rear end of the secondengagement concave portion 2172 b are each the same length L2.

Here, note that an inner peripheral ring 3000 and a concave portion 2220formed on the outer peripheral surface of the outer peripheral ring 2000are the same as explained in the above-mentioned embodiment, and so, theexplanation thereof is omitted.

As described above, in the sealing device according to this referenceexample, too, the same operational effects as in the case of theabove-mentioned embodiment can be obtained. In addition, in the case ofthe sealing device according to this reference example, even if theperipheral length of the outer peripheral ring 2000 becomes longer dueto its thermal expansion so that the outer peripheral ring 2000 is putinto a state where the tip end of the first engagement convex portion2171 a is in abutment against the rear end of the second engagementconcave portion 2172 b, and the tip end of the second engagement convexportion 2171 b is in abutment against the rear end of the firstengagement concave portion 2172 a, a state will be maintained in which agap S is formed between the end faces of the inner peripheral side inthe cut portion (refer to FIG. 137). Accordingly, it is possible tosuppress the inner peripheral ring 3000 from being damaged by the endfaces of the inner peripheral side in the cut portion being clamped orpinched with each other. Here, note that it is preferable toappropriately set the gap S with which damage to the inner peripheralring 3000 will not be caused, according to the service or useenvironment, the rigidity of the inner peripheral ring 3000, etc., andto set a difference between L1 and L2 according to the gap S.

Here, note that as explained in the beginning of this reference example,the construction of the special step cut according to this referenceexample can be applied not only to the above-mentioned embodiment, butalso to a case where in each of the above-mentioned individual referenceexamples and individual practical examples, the special step cut isadopted for an abutment joint portion of an outer peripheral ring.

<Modification of the Thirty-First Reference Example>

Summary

Reference will be made to a case where the construction of the specialstep cut according to the above-mentioned thirty-first reference exampleis applied to the construction of the sealing device according to theeleventh reference example.

That is, a sealing device according to the eleventh reference example ofthe present disclosure, which is fitted into an annular groove formed inan outer periphery of a shaft so as to seal an annular gap between saidshaft and a housing which rotate relative to each other, thereby to holda fluid pressure in a region to be sealed which is constructed such thatthe fluid pressure therein changes, comprising: an outer peripheral ringmade of resin that is in intimate contact with a side wall surface ofsaid annular groove at a low pressure side thereof, and slides withrespect to an inner peripheral surface of a shaft hole in said housingthrough which said shaft is inserted; and an inner peripheral ring madeof a rubber-like elastic body that is in intimate contact with an innerperipheral surface of said outer peripheral ring and a groove bottomsurface of said annular groove, respectively, thereby to push said outerperipheral ring toward an outer peripheral surface side thereof; whereinsaid outer peripheral ring is formed on its outer peripheral surfacewith a concave portion which extends from an end of a high pressure sideto a position which does not arrive at an end of a low pressure side, soas to introduce fluid thereinto from the high pressure side, in a statewhere said outer peripheral ring is fitted in a normal direction; andwherein said outer peripheral ring is formed with a fitting directiondetection passage that forms a flow passage through which fluid to besealed leaks from the high pressure side to the low pressure side, in astate where said outer peripheral ring is fitted in a reverse direction.

And, it is further characterized in the following features: an abutmentjoint portion is formed on said outer peripheral ring at one place in acircumferential direction thereof; said abutment joint portion, by beingcut in a stepwise shape even when seen from any of an outer peripheralsurface side and opposite side wall surface sides thereof, is formed, onan outer peripheral side at one side thereof of a cut portion, with afirst engagement convex portion and a first engagement concave portion,and is also formed, on the outer peripheral side at the other sidethereof of the cut portion, with a second engagement concave portioninto which said first engagement convex portion is engaged, and a secondengagement convex portion which is engaged into said first engagementconcave portion; it is constructed such that a length from one end faceof an inner peripheral side in the cut portion to a tip end of the firstengagement convex portion is longer than a length from the one end faceof the inner peripheral side in the cut portion to a rear end of thefirst engagement concave portion, and a length from the other end faceof the inner peripheral side in the cut portion to a tip end of thesecond engagement convex portion is longer than a length from the otherend face of the inner peripheral side in the cut portion to a rear endof the second engagement concave portion; and said fitting directiondetection passage is composed of a gap that is formed at an innerperipheral surface side in the abutment joint portion of said outerperipheral ring so as to extend in an axial direction, and a groove thatis formed at a side wall surface side of said outer peripheral ring atthe low pressure side in a state where said outer peripheral ring isfitted in the reverse direction, and extends in a radial direction so asto be connected with said gap.

With the above construction, the operational effects of the sealingdevice according to the eleventh reference example are obtained, and atthe same time, the operational effects of the sealing device accordingto the thirty-first reference example are obtained.

Specific Example

As described above, in the thirty-first reference example, the gap Sextending in the axial direction will always be formed at the innerperipheral surface side in the abutment joint portion 2170 of the outerperipheral ring 2000, as mentioned above. Accordingly, this gap S can beutilized as the fitting direction detection passage explained in theeleventh reference example. That is, it becomes possible to form thefitting direction detection passage by forming on the side wall surfaceof the outer peripheral ring 2000 at the low pressure side (L) a grooveextending in a radial direction so as to be connected with theabove-mentioned gap S. In other words, by forming a groove 2420 aextending in a radial direction, as shown by a broken line in FIG. 79,the fitting direction detection passage can be formed by the gap S andthe groove 2420 a referred to above.

Here, note that in the above-mentioned eleventh reference example, theouter peripheral ring 2000 may be formed with only a fitting directiondetection passage which is composed of such a gap S and such a groove2420 a, or a construction may instead be adopted in which the outerperipheral ring 2000 is formed with both a fitting direction detectionpassage which is composed of the first groove 2324 and the second groove2420 referred to above, and a fitting direction detection passage whichis composed of the gap S and the groove 2420 a.

(Others)

The characteristic constructions in the above-mentioned individualreference examples and individual practical examples are not limited tothe cases in which a particular explanation has been made in thereference examples and practical examples, but may be combined with oneanother in a suitable manner as much as possible.

For example, a characteristic construction in the second referenceexample can be applied to the above-mentioned individual referenceexamples and individual practical examples except for the fourth throughtenth and nineteenth through thirtieth reference examples.

In addition, a characteristic construction in the third referenceexample can be applied to the above-mentioned individual referenceexamples and individual practical examples except for the fourth throughtenth and twenty-third through thirtieth practical examples.

Further, individual characteristic constructions in the first throughfourth practical examples can be applied to the above-mentionedindividual reference examples, respectively, except for the eighteenth,twenty-fourth, twenty-fifth and twenty-sixth reference examples. In thefollowing, particularly preferable combinations will be explained.

(Combination of the First Practical Example and the Thirty-FirstReference Example)

It is preferable to apply the construction of the abutment joint portion2170 shown in the thirty-first reference example as illustrated in FIG.136 and FIG. 137 to the abutment joint portion 2100 of the outerperipheral ring 2000 which is formed with a plurality of concaveportions 2220, 2220 a, 2220 b, 2220 c shown in the first practicalexample and in the various modifications thereof explained withreference to the above-mentioned FIG. 19 through FIG. 28.

(Combination of the Tenth Reference Example and the Thirty-FirstReference Example)

It is preferable to apply the construction of the abutment joint portion2170 shown in the thirty-first reference example as illustrated in FIG.136 and FIG. 137 to the abutment joint portion 2100 of the outerperipheral ring 2000 which is formed with the inclined surface 2323shown in the tenth reference example explained with reference to theabove-mentioned FIG. 71 through FIG. 75. However, it is necessary toform the inclined surface 2323 as shown in FIG. 73, for example, on theabutment joint portion 2170, too.

(Combination of the First Practical Example, the Thirteenth ReferenceExample and the Thirty-First Reference Example)

It is preferable to further apply the construction of the abutment jointportion having the fitting direction detection concave portion 2112 dexplained in the thirtieth reference example and in the modificationthereof described with reference to FIG. 92 through FIG. 102 to theabove-mentioned construction which is the combination of the firstpractical example and the thirty-first reference example.

EXPLANATION OF REFERENCE NUMERALS AND CHARACTERS

-   -   1000 sealing device    -   2000 outer peripheral ring    -   2100 abutment joint portion    -   2111 first engagement convex portion    -   2111 a side wall surface    -   2111 b inner peripheral surface    -   2111 c tip end face    -   2112 second engagement convex portion    -   2112 a side wall surface    -   2112 b inner peripheral surface    -   2112 c tip end face    -   2112 d fitting direction detection concave portion    -   2121 first engagement concave portion    -   2121 a side wall surface    -   2121 b outer peripheral surface    -   2121 c end face    -   2122 second engagement concave portion    -   2122 a side wall surface    -   2122 b outer peripheral surface    -   2122 c end face    -   2131 end face    -   2132 end face    -   2132 a low pressure side end face    -   2132 b high pressure side end face    -   2150 abutment joint portion    -   2151 engagement convex portion    -   2151 a side wall surface    -   2151 b inner peripheral surface    -   2151 c end face    -   2152 engagement concave portion    -   2152 a side wall surface    -   2152 b outer peripheral surface    -   2152 c end face    -   2155 engagement convex portion    -   2155 a inclined surface    -   2155 c end face    -   2156 engagement concave portion    -   2156 a inclined surface    -   2156 c end face    -   2170 abutment joint portion    -   2171 a first engagement convex portion    -   2171 b second engagement convex portion    -   2172 a first engagement concave portion    -   2172 b second engagement concave portion    -   2210 low pressure side convex portion    -   2211, 2211 a, 2211 b, 2211 c rib    -   2211 c 1 inclined surface    -   2212, 2212 a, 2212 b, 2213 and 2214 convex portion    -   2215 outer peripheral convex portion    -   2220, 2220 a, 2220 b, 2220 c, 2223 concave portion    -   2221, 2221 a, 2221 b third concave portion    -   2222, 2222 a, 2222 b fourth concave portion    -   2311 convex portion    -   2312, 2313 inner peripheral convex portion    -   2314 convex portion    -   2315 convex portion    -   2316 inner peripheral convex portion    -   2321 mounting groove    -   2322 second concave portion    -   2323 inclined surface    -   2324 first groove    -   2400 protrusion portion    -   2420 second groove    -   2420 a groove    -   2510, 2511 convex portion    -   2520 concave portion    -   2571 a engagement convex portion    -   3000, 3100, 3110, 3120, 3130, 3140, 3150, 3160, 3170, 3180,        3190, 3200, 3210 inner peripheral ring    -   3111, 3112, 3113, 3121, 3122, 3123, 3124, 3131, 3132, 3133,        3141, 3142 seal portion    -   3151, 3152, 3153, 3161 annular groove    -   3181, 3191, 3201, 3211 groove    -   3500, 3510 position limiting ring    -   4000 shaft    -   4100, 4110, 4120, 4130, 4140, 4150, 4160, 4170, 4180 annular        groove    -   4121 annular concave portion    -   4122 annular convex portion    -   4131 convex portion    -   4141, 4151, 4161, 4171, 4180, 4181 concave portion    -   5000 housing    -   5110 large diameter portion    -   5120 small diameter portion    -   5130 stepped surface

The invention claimed is:
 1. A sealing device which is fitted into anannular groove formed in an outer periphery of a shaft so as to seal anannular gap between said shaft and a housing which rotate relative toeach other, thereby to hold a fluid pressure in a region to be sealedwhich is constructed such that the fluid pressure therein changes,comprising: an outer peripheral ring made of resin that is in intimatecontact with a side wall surface of said annular groove at a lowpressure side thereof, and slides with respect to an inner peripheralsurface of a shaft hole in said housing through which said shaft isinserted; and an inner peripheral ring made of a rubber-like elasticbody that is in intimate contact with an inner peripheral surface ofsaid outer peripheral ring and a groove bottom surface of said annulargroove, respectively, thereby to push said outer peripheral ring towardan outer peripheral surface side thereof; wherein a portion in saidouter peripheral ring which slides with respect to the inner peripheralsurface of said shaft hole is constructed by a raised portion which isformed so as to extend along a majority of a circumferential directionwhile changing its position to a high pressure side and a low pressureside in an alternate manner.
 2. A sealing device which is fitted into anannular groove formed in an outer periphery of a shaft so as to seal anannular gap between said shaft and a housing which rotate relative toeach other, thereby to hold a fluid pressure in a region to be sealedwhich is constructed such that the fluid pressure therein changes,comprising: an outer peripheral ring made of resin that is in intimatecontact with a side wall surface of said annular groove at a lowpressure side thereof, and slides with respect to an inner peripheralsurface of a shaft hole in said housing through which said shaft isinserted; and an inner peripheral ring made of a rubber-like elasticbody that is in intimate contact with an inner peripheral surface ofsaid outer peripheral ring and a groove bottom surface of said annulargroove, respectively, thereby to push said outer peripheral ring towardan outer peripheral surface side thereof; wherein said outer peripheralring is formed on its outer peripheral surface with a plurality ofrecessed portions which are spaced from one another along a majority ofa circumferential direction and which each extend from an end of a highpressure side to a position which does not arrive at an end of a lowpressure side, so as to introduce fluid thereinto from the high pressureside; and wherein raised portions each formed between adjacent recessedportions are formed so as to extend from the low pressure side towardthe high pressure side as they go in the sliding direction of said outerperipheral ring with respect to said housing.
 3. A sealing structurewhich is provided with: a shaft and a housing that rotate relative toeach other; and a sealing device that is fitted into an annular grooveformed in an outer periphery of said shaft so as to seal an annular gapbetween said shaft and said housing, thereby to hold a fluid pressure ina region to be sealed which is constructed such that the fluid pressuretherein changes; wherein said sealing device comprises: an outerperipheral ring made of resin that is in intimate contact with a sidewall surface of said annular groove at a low pressure side thereof, andslides with respect to an inner peripheral surface of a shaft hole insaid housing through which said shaft is inserted; and an innerperipheral ring made of a rubber-like elastic body that is in intimatecontact with an inner peripheral surface of said outer peripheral ringand a groove bottom surface of said annular groove, respectively,thereby to push said outer peripheral ring toward an outer peripheralsurface side thereof; said outer peripheral ring is formed on its outerperipheral surface with a plurality of recessed portions which arespaced from one another along a majority of a circumferential directionand which extend from an end of a high pressure side to a position whichdoes not arrive at an end of a low pressure side, so as to introducefluid thereinto from the high pressure side; and raised portions eachformed between adjacent recessed portions are formed so as to extendfrom the low pressure side toward the high pressure side as they go inthe sliding direction of said outer peripheral ring with respect to saidhousing.
 4. A sealing device which is fitted into an annular grooveformed in an outer periphery of a shaft so as to seal an annular gapbetween said shaft and a housing which rotate relative to each other,thereby to hold a fluid pressure in a region to be sealed which isconstructed such that the fluid pressure therein changes, comprising: anouter peripheral ring made of resin that is in intimate contact with aside wall surface of said annular groove at a low pressure side thereof,and slides with respect to an inner peripheral surface of a shaft holein said housing through which said shaft is inserted; and an innerperipheral ring made of a rubber-like elastic body that is in intimatecontact with an inner peripheral surface of said outer peripheral ringand a groove bottom surface of said annular groove, respectively,thereby to push said outer peripheral ring toward an outer peripheralsurface side thereof; wherein said outer peripheral ring is formed onits outer peripheral surface with a plurality of recessed portions whichare spaced from one another along a majority of a circumferentialdirection and which each extend from an end of a high pressure side to aposition which does not arrive at an end of a low pressure side, so asto introduce fluid thereinto from the high pressure side; and whereinraised portions each formed between adjacent recessed portions areformed so as to extend from the high pressure side toward the lowpressure side as they go in the sliding direction of said outerperipheral ring with respect to said housing.
 5. A sealing structurewhich is provided with: a shaft and a housing that rotate relative toeach other; and a sealing device that is fitted into an annular grooveformed in an outer periphery of said shaft so as to seal an annular gapbetween said shaft and said housing, thereby to hold a fluid pressure ina region to be sealed which is constructed such that the fluid pressuretherein changes; wherein said sealing device comprises: an outerperipheral ring made of resin that is in intimate contact with a sidewall surface of said annular groove at a low pressure side thereof, andslides with respect to an inner peripheral surface of a shaft hole insaid housing through which said shaft is inserted; and an innerperipheral ring made of a rubber-like elastic body that is in intimatecontact with an inner peripheral surface of said outer peripheral ringand a groove bottom surface of said annular groove, respectively,thereby to push said outer peripheral ring toward an outer peripheralsurface side thereof; said outer peripheral ring is formed on its outerperipheral surface with a plurality of recessed portions which arespaced from one another along a majority of a circumferential directionand which extend from an end of a high pressure side to a position whichdoes not arrive at an end of a low pressure side, so as to introducefluid thereinto from the high pressure side; and raised portions eachformed between adjacent recessed portions are formed so as to extendfrom the high pressure side toward the low pressure side as they go inthe sliding direction of said outer peripheral ring with respect to saidhousing.